UNIT 1

Living Things and Their

Environment

Photo Credit: http://www.flyingfourchette.com/2013/05/25/around-ubud/

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 Suggested time allotment: 8 to 10 hours

Unit 1
MODULE
Respiratory and Circulatory

1 Systems
Working with Other Organ
Systems

Overview
Your body is a fascinating creation that can carry out incredible tasks and
activities. It is like a machine that is able to function with proper organization of parts
and systems. However, our bodies also require proper care and maintenance. It is just
fitting to keep going with a healthy lifestyle to ensure that each part is maintained
appropriately while getting the most out of it.

In the past, you were introduced to the different levels of organizations in the
human body and the mechanisms involved in it. You have learned that the human body
is composed of different systems, which are collections of cells, tissues, and organs,
each of which has a special job that keeps you alive. Whether you eat, play, dance,
sing, or sleep; each part of your organ systems performs particular functions. You also
discovered how the digestive system breaks down food to nourish your whole body.

Now, you will learn how the different structures of the circulatory and
respiratory systems work together to transport oxygen-rich blood and nutrients
to the different parts of the body. You will also understand the prevention,
detection, and treatment of diseases affecting the respiratory and circulatory
systems.

At the end of this module, you are expected to:

1. explain the mechanism on how the respiratory and circulatory systems work
together to transport nutrients, gases, and molecules to and from the different
parts of the body;
2. infer how one’s lifestyle can affect the functioning of respiratory and
circulatory systems.

Respiratory system is made up of the organs in the body that help us to

breathe. Just remember that the word respiration is linked to breathing. Circulatory

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system is responsible for distributing materials throughout the body. Take note that
circulation means transportation or movement in circles. Both systems are essentially
meant for each other. The common purpose could not be attained without the other
system.

In Module 1, you will be able to answer the following key questions:

 How do the respiratory and circulatory systems work with each other?

 How do the diseases in the circulatory and respiratory systems begin to develop?

 How can a person’s lifestyle affect the performance of the respiratory and
circulatory systems?

Pre-assessment
Direction: Fill in the K-W-H-L Chart below to assess your prior knowledge and
understanding of the topic, Respiratory and Circulatory Systems, Working with the
other Organ Systems.

K W H L
What do I know? What do I want to How can I find out What did I learn?
find out? what I want to
learn?

Skills I expect to use:

The Human Breathing System

Breathe in and out. Notice your chest and belly moving and feel the soft air passing from
the nose. Listen to the quiet sounds of breathing in and out. Imagine the air moving from the
nose into the throat, through the air tubes, and into the airsacs. The parts of the respiratory
system that are in charge of supplying oxygen are the nose, nasal passageways, windpipe,
lungs, and diaphragm. In the nose and nasal passages, the entering air is made warm, damp,

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and clean of unknown particles. Next, the air moves down through the trachea, bronchi,
bronchioles, and alveoli. Trachea is the empty tube that serves as passageway of air into the
lungs. Bronchi are the two branching tubes that connect the trachea to the lungs. Bronchioles
are the hairlike tubes that connect to the alveoli. Alveoli are the airsacs that allow gas
exchange in the lungs.
Perform the following simple activity to widen your understanding of the human
breathing system.
Activity 1

PART A
What a Bunch of Grapes!
Objective:
 Identify the key parts of the breathing system

Materials:
Bunch of grapes
(or any other bunch of fruits or vegetables such as arosep or lato (seaweed), lanzones,
cauliflower, etc.)

Procedure:
1. Hold up the bunch of grapes. Let the bunch of grapes represent the breathing
system.
2. Within your group, locate the parts of the breathing system: the main stem as the
trachea, the large branching stems as the bronchi, and all the little stems as the
bronchioles. The individual grapes are the airsacs or alveoli.
3. One by one, gently take out some of the grapes to expose more of the branching
stems (bronchioles). Observe its structure.
4. Trace the pathway of oxygen using the “Bunch of Grapes” model. Note that air
moves from the nose (nasal cavity) and mouth (oral cavity) to the trachea,
bronchi, bronchioles, and then into the alveoli (air sacs). The air we breathe
carries the gas oxygen. When we breathe, the oxygen goes to the lungs.

BRONCHI
TRACHEA

BRONCHIOLES
ALVEOLI

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PART B
Figure 1. The bunch of grapes model of the breathing system

Objective:
 Describe the function of each part of the breathing system

Procedure:
1. Refer to the diagram, and check your understanding of the breathing system by
labeling each part and giving its functions in the box corresponding to the part.

Figure 2. The human respiratory system

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Guide Questions:
Q1. What does each part of the “Bunch of Grapes” model represent, in relation to the
breathing system?
______________________________________________________________________

Q2. How will you describe the pathway of oxygen in the breathing system?
______________________________________________________________________

Q3. What will happen if one part of the system fails to carry out its function properly?
______________________________________________________________________

KEY CONCEPTS
The air we breathe goes through the nose, nasal passages, and then
through the trachea or windpipe, which separates into two branches,
called bronchial tubes or bronchi, one entering each lung. The bronchi subdivide
many times inside the lungs, analogous to the branching pattern of grapes, finally
becoming hairlike tubes called bronchioles. In the last part of the terminal
bronchioles are tiny bubble-like bunch of structures called alveoli or airsacs.

Previously, you have already learned about the essential parts of the breathing
system and their functions. Now, you will understand the mechanism and activities of
the lungs and the diaphragm.

Have you experienced being in a jam-packed train? You almost certainly could
not wait to get out where there are fewer people so you could freely move. This is
analogous to the process that makes air move in and out of your lungs. The air
molecules are either crowded outside and tend to get into the lungs where there are
fewer air molecules (inhalation), or they tend to get outside because they are too
crowded inside the lungs (exhalation). When you breathe in, your diaphragm muscle
contracts downward and rib muscles pull upward causing air to fill up the lungs. Can
you explain why? Well, when your diaphragm goes lower and ribs shift up, they provide
more breathing space in your chest. This also reduces the force on your lungs so the air
will move in from the outside. Breathing out is a reverse process. Your diaphragm
loosens up and the ribs and lungs thrust in, causing the gas to be exhaled.

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Activity 2
Bottled Balloons
Objectives:
 Explain how the lungs work
 Describe how the movement of the diaphragm helps the air go in and out
of the lungs

Materials:
1 two-liter empty plastic bottle 1 sturdy straw 1 pair of scissors
3 balloons (1 big, 2 small) 5 rubber bands
Procedure:
1. Using a pair of scissors, cut the bottom out of the 2-liter plastic bottle.
2. Create two holes that are apart from each other in the cap of the plastic bottle. Make
sure that each hole is just big enough for a straw to fit through.
3. Stick the two straws through the two holes of the bottle cap.
4. Place one balloon on the end of each straw, and secure them with rubber bands, as
shown in the figure below.

Figure 3. The two straws with the balloons are inserted into the plastic bottle cap.

5. Stick the balloon ends of the straws through the bottle opening and screw the lid on
tightly.
6. Stretch out the larger balloon and place it over the open bottom of the bottle. Secure
it with the rubber band as tightly as possible. Refer to the diagram of the finished lung
model below.

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Figure 4. A constructed model of the human chest cavity
5. Pull the larger balloon down; that is, away from the bottle, in order to blow up the two
small balloons.
6. Push the larger balloon towards the bottle in order to let the air out of the two small
balloons.
7. Write down your observations.

Guide Questions:
Q4. What does each part of the constructed lung model represent?
______________________________________________________________________

Q5. What happens as you pull down the balloon at the bottom of the model?
______________________________________________________________________

Q6. What happens as you push up the balloon?

______________________________________________________________________

Q7. How does the movement of the diaphragm cause the air to go in and out of the
lungs?
______________________________________________________________________

Q8. What might happen if you prick the balloon?

______________________________________________________________________

KEY CONCEPTS
When you breathe in, or inhale, the diaphragm muscle contracts. Inhaling moves
the diaphragm down and expands the chest cavity. Simultaneously, the ribs move up and
increase the size of the chest cavity. There is now more space and less air pressure inside
the lungs. Air pushes in from the outside where there is a higher air pressure. It pushes into
the lungs where there is a lower air pressure. When you breathe out, or exhale, the
diaphragm muscle relaxes. The diaphragm and ribs return to their original place. The chest
cavity returns to its original size. There is now less space and greater air pressure inside the
lungs. It pushes the air outside where there is lower air pressure.

Why do we believe that life is possible only on planets where oxygen is

present? Oxygen is necessary for life to exist. Without it, the cells in the body
would not be able to release the energy in food for power, and they would die
within minutes. When you inhale air, your respiratory system gets oxygen. When
you exhale, carbon dioxide is released. How do the respiratory and circulatory
systems work together to carry out their common purpose?

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 Perform the next activity to learn more about the gas exchange that takes
place in the respiratory and circulatory systems.

Activity 3
Just Go with the Flow!
Objectives:
 Describe blood flow and gas exchange within the heart, circulatory system, and
lungs
 Explain the mechanism of how the respiratory and circulatory systems work
together

Materials:
Paper strips Rope or ribbon
Marking pen Chalk

Source:
Glencoe/McGraw-Hill -
http://www.glencoe.com/sites/common_assets/health_fitness/gln_health_fitness_zone/pdf/heart
_rate_monitor_activities/the_heart/the_heart_activity_2.pdf
Procedure:
1. Perform the activity with your group mates (7-8 persons).

2. Assign and label different areas in the outdoor setting as: lungs, left atrium, left
ventricle, artery/aorta, capillary, veins, right ventricle, and right atrium.

3. Using the marking pen, write down the word oxygen on as many paper strips as
you can and place them in the lung area. The capillary area should have papers
with carbon dioxide written on them.

4. Use the chalk to mark and define the different areas such as what is given in the
diagram below. Assign some members of your group to stand still on the different
marked areas.
LUNGS
Veins Aorta Capillary

Right Atrium Left Atrium

Right Ventricle Left Ventricle

9 Figure 5. Illustration of the gas exchange activity

 5. Choose two members from the group to take the trip around the different posts.
Let the partners start the tour in the lung area and together pick up a paper
labeled as oxygen from another member standing at his post. They should carry
the strip of paper to the heart, passing through the left atrium, and then to the left
ventricle. As the partners go to every station, they must leave a trail of rope or
ribbon held by another member in a designated area, until the path of the journey
is completely traced.

6. Partners must run along the chalk marks representing the arteries into the
capillary area.

7. Tell the partners to exchange the strip of paper representing oxygen for a piece
of paper representing carbon dioxide with a member in his designated area.

8. Make the partners run along the chalk marks representing the veins into the
heart area, first to the right atrium, then to the right ventricle.

9. The partners must then run back into the lung area where the process begins
again. When there are no more strips of paper, the activity is over. The leader
may want to keep placing new papers into designated areas to keep the game
going on longer.

10. After the activity, record your observations and answer the guide questions.

Guide Questions:
Q9. How do the heart and the lungs work together?
______________________________________________________________________

Q10. What takes place when you inhale and exhale?

______________________________________________________________________
Q11. What does blood deliver to every part of the body?
______________________________________________________________________
Q12. Why is oxygen important to your body?
______________________________________________________________________
Q13. How will you describe the sequence of oxygen, carbon dioxide, and blood flow in
your own words?
______________________________________________________________________

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ENRICHMENT ACTIVITY

In the given framework of the human body below, illustrate the blood flow
and gas exchange in the respiratory and circulatory systems using diagrams and
arrows. Color your work to show the distinction of oxygen and carbon dioxide
carried in the blood.

KEY CONCEPTS
Air first enters your lungs and then into the left part of your heart. It is then driven by your
heart into the bloodstream, all the way through your body. The heart pumps blood, which
transports essential nutrients, oxygen, and other chemicals to every cell in your body. Once
it reaches the cells, oxygen processes the nutrients to release energy. Carbon dioxide is
given off during this process. The blood delivers carbon dioxide into the right portion of your
heart, from which it is pumped to the lungs. Carbon dioxide leaves your body through the
lungs when you exhale.
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 The circulatory system is the life support structure that nourishes your
cells with nutrients from the food you eat and oxygen from the air you breathe. It
can be compared to a complex arrangement of highways, avenues and lanes
connecting all the cells together into a neighborhood. Sequentially, the
community of cells sustains the body to stay alive. Another name for the
circulatory system is the cardiovascular system.
The circulatory system functions with other body systems to deliver
different materials in the body. It circulates vital elements such as oxygen and
nutrients. At the same time, it also transports wastes away from the body.

Figure 6. The human circulatory system

The following are the three major parts of the circulatory system, with their roles:

1. Heart – pumps the blood throughout the body

2. Blood vessel – carries the blood throughout the body

 Arteries - carry oxygenated blood away from the heart to the cells,
tissues and organs of the body
 Veins - carry deoxygenated blood to the heart
 Capillaries - the smallest blood vessels in the body, connecting the
smallest arteries to the smallest veins
- the actual site where gases and nutrients are exchanged

3. Blood – carries the materials throughout the body

CIRCULATION

TYPE OF CIRCULATION DESCRIPTION DIAGRAM

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 Movement of blood from
the heart, to the lungs,
1. Pulmonary Circulation
and back to the heart

sln.fi.edu/biosci/systems/ pulmonary.html

Movement of blood
through the tissues of the
2. Coronary Circulation
heart

sln.fi.edu/biosci/systems/ pulmonary.html

Movement of blood from

3. Systemic Circulation the heart to the rest of the
body, excluding the lungs

sln.fi.edu/biosci/systems/ pulmonary.html

Activity 4
Let’s Organize!

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Objectives:
 Identify the components of the circulatory system
 Explain the different types of circulation

Procedure:
Using the given graphic organizer, fill in the missing parts, description, and
functions to complete the entire concept.

CIRCULATORY SYSTEM

Parts

Blood
Vessel

Pumps the blood Carries

throughout the the materials
body throughout the body

Types

CIRCULATION

Types

Systemic
Circulation

The Human Heart Movement of blood through

the tissues of the heart

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 Do you know how big your heart is? Take a look at your fist. The heart is a
hollow muscle, as seen in Figure 7, which is just as big as your fist. It has four
chambers with specific tasks to do: two ventricles and two atria. The atria are
the receiving chambers of the heart, accepting blood from the body (right
atrium) and from the lungs (left atrium). The ventricles are the pumping
chambers, moving blood to the lungs (right ventricle) and into the body (left
ventricle).

Photo Credit:
Alexanderpiavas134
The heart has two pumps. Each pump (Public Domain)
has two chambers, the upper and lower
Figure 7. Photo of an actual human heart
chambers. The upper chamber is the atrium Right Pulmonary
Artery
that receives blood coming in from the veins. Left Pulmonary
The lower chamber is the ventricle that forces Artery

the blood out into the arteries. There is a

valve between each atrium and ventricle to
prevent the blood from flowing backwards.
The valves are like one-way doors that keep
the blood moving in only one direction. Valves
control movement of blood into the heart Valve
chambers and out to the aorta and the
pulmonary artery. Refer to Figure 8.

Q14. Explain how the heart works.

Figure 8. The major divisions of the heart
Q15. Evaluate how the heart can be compared to a
mechanical pump.

All of the muscle tissues of the heart

do not contract at the same time. Different
parts of the heart contract at different times.
When the top portion contracts, the bottom
part relaxes. When the bottom contracts, the
top relaxes. When a chamber contracts, it
becomes smaller and the blood inside gets
squeezed or pumped out.

To have a better understanding of how

your heart works, do the next simple activity.
Source: sln.fi.edu/biosci/systems/ pulmonary.html
Figure 9. The detailed parts of the heart

Activity 5

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 Pump It!
Objectives:
 Describe how the heart functions
 Explain how blood is pumped by the heart

Materials:
1 beaker or wide mouthed jar 1 large pan or sink
1 balloon adhesive tape
2 flexible drinking straws water
1 pair of scissors

Source:
Home Science Tools -
http://www.hometrainingtools.com/make-a-heart-pump-science-project/a/1852/

Procedure:
1. Fill the jar half full of water.
2. Cut the neck of the balloon off at the part where it starts to widen into a balloon.
Set the neck part aside to be used later on.
3. Stretch the balloon over the opening of the jar, pulling it down as tightly as you
can. The flatter you can get the surface of the balloon, the better.
4. Carefully poke two holes in the surface of the balloon. Make them about an inch
apart from each other and near opposite edges of the jar.
5. Stick the long part of a straw into each hole. The straws should fit securely in the
holes so no air can get through around the straws.
6. Slide the uncut end of the balloon neck onto one of the straws and tape it around
the straw.
7. Set your pump in a large pan or the sink to catch the pumped water. Bend the
straws downward. Gently press in the center of the stretched balloon and watch
what happens to the water in the jar.
8. Refer to the photo below to know what your setup must look like.

Source: http://www.hometrainingtools.com/make-a-heart-pump-science-project/a/1852/
Guide Questions:
Figure 10. The heart pump model

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 Q16. What does the water inside the jar represent?
______________________________________________________________________

Q17. How will you compare the heart pump model and the human heart?
______________________________________________________________________

Q18. How does the heart function as a pump?

______________________________________________________________________

Q19. Will the heart model be able to function properly if the straw is blocked? Explain
your answer.
______________________________________________________________________

KEY CONCEPTS
The heart is a hollow muscular organ, about the size of your fist, which is located in
the center of your chest between the lungs. It is a double pump that pumps on the left and
right sides. Every side is divided into two chambers, the atrium and the ventricle, each of
which has left and right portion, totaling to four chambers altogether. The top chamber is the
atrium (plural: atria). The bottom chamber is called the ventricle. The valve acts as a one-
way door, allowing blood to flow either forward into the next chamber, or out of the heart.

Since you have already understood how the heart functions and how blood is
pumped all over the body, you are now ready to check your own heart rate. Your heart
beat is the sound that your heart makes as it pumps blood. Let us further investigate
about it in the next activity.

Activity 6
The Rhythm of My Heart
Objectives:
 Measure and describe your pulse (heart rate) after several different activities
 Explain how to use different time intervals to measure your heart rate

Materials:
Stopwatch / timer
Data Logbook

Procedure:
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 1. Sit quietly for a few minutes before beginning the activity.

2. When you are ready, place your first two fingers either on your neck or on the
inside of your wrist and locate your pulse.

3. Once you find your pulse, start the watch, and for 60 seconds, count the number
of beats you feel. That is your pulse.

4. Try the experiment again, but this time count for only 30 seconds. When you are
done, multiply your count by two. Compare your pulses.

5. Repeat by counting for 15 seconds and multiplying your count by four, then
counting for 10 seconds and multiplying by six, and so on.

6. Once you have determined your resting pulse, go to a place where you can
exercise vigorously for at least one minute. Exercise of this sort might include a
fast jog, running stairs, skipping rope, or doing pushups. When you are done, you
should be breathing hard.
If you know that you have
TAKE a serious medical condition,
CARE! do not perform this activity.

7. Choose the length of the test you wish to perform and find your pulse again.

8. Compare your resting pulse with your pulse after exercise.

9. After the activity, record your observations and answer the guide questions.

Guide Questions:
Q20. What was your calculated resting pulse?
______________________________________________________________________

Q21. What was your pulse after exercising?

______________________________________________________________________

Q22. How would you differentiate your heart rates before and after exercising?

______________________________________________________________________

Q23. What is the advantage of timing for a full minute to find your pulse?
______________________________________________________________________

Q24. What is the advantage of timing over a shorter period of time, especially when you
have just finished exercising?
______________________________________________________________________

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Q25. According to statistics, the maximum heart rate should be 220 minus a person's
age. How would you interpret your highest heart rate in relation to that given number?
______________________________________________________________________

KEY CONCEPTS
Each time your heart beats, it delivers oxygen-rich blood to your body, which allows
it to function properly. Your heart rate or pulse is the number of times your heart beats in
a minute (BPM or beats per minute). Shorter time intervals may be used in taking the
pulse as long as it comes to 60 seconds upon multiplying with a factor. When you are
resting, your heart rate slows down, as your body does not need as much blood as it does
when you exercise.

Now that you are aware that strenuous activities may lead to an increased heart
rate, you can now monitor your activities to avoid the dangers of cardio-respiratory
diseases. Another risk factor that drastically increases heart rate and decreases the
amount of oxygen in the blood is smoking cigarettes. Perform the next simple activity to
learn more about the negative effects of cigarettes on a person’s circulatory and
respiratory systems.

Activity 7

Cigarette Smoking Is Dangerous to Your

Health
Objective:
 Explain the negative effects of cigarette smoking on the circulatory and
respiratory systems

Materials:
meta cards
marking pen
adhesive tape

Procedure:

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 1. Look at the picture of the smoker’s body below, and take note of the illnesses
that might develop due to cigarette smoking.

Photo Credit: http://www.clarkisit.com/smoking-kills/

Figure 11. The smoker’s body

2. Within your group, brainstorm ideas about the effects of cigarette smoking on
a person’s respiratory and circulatory systems using the meta plan strategy.

3. Choose a group member who will act as moderator to solicit all the ideas of
the members about the negative effects of cigarette smoking on the
circulatory and respiratory systems.

4. Each participant must give at least three negative effects of cigarette smoking
on both circulatory and respiratory systems. Answers must be written on the
blank cards.

5. The moderator collects the meta cards and reads each one of them while
showing the cards to the whole group so that everyone can read them.

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 6. After discussing the ideas within the group, stick and organize all the
responses on the blackboard to categorize which answer falls under the
respiratory and circulatory systems. Refer to the example given below.

Cigarette Smoking

Circulatory System Respiratory System

7. Group the cards with identical or similar statements together into clusters,
allowing multiple statements to emerge clearly.

8. Choose a representative to explain the work of the group.

KEY CONCEPTS
Cigarette smoking harms nearly every organ in the body, causing many illnesses
and affecting health in general. The negative effects of smoking on circulatory system
include increased heart rate and blood pressure, coronary heart disease, arteriosclerosis,
and vascular diseases. The respiratory diseases caused by smoking are chronic
bronchitis, emphysema, asthma, cough, colds, tuberculosis, lung cancer, and other
respiratory infections.

Enrichment Activity

Gather and write down information about the different diseases affecting the respiratory
and circulatory systems, and their common causes.

The leading causes of death around the world are diseases affecting the
respiratory and circulatory systems. However, they can be prevented simply by having a
lifestyle that promotes wellness. Circulatory and respiratory diseases begin to develop
with unhealthy living. Symptoms of these illnesses must not be neglected and
appropriate cure must be given immediately. Carry out the next task to further broaden
your learning.

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Activity 8

Prevention Is Better Than Cure

Objective:
 Identify ways of detecting and preventing diseases in the respiratory and
circulatory systems
 Appreciate the importance of a healthy lifestyle in avoiding such diseases

Procedure:
1. With your groupmates, create a story that illustrates various ways of preventing
diseases that affect the respiratory and circulatory systems. You must also show
the importance of keeping our bodies healthy and free from illnesses.

2. Present the story that you made in front of the class by means of role-playing.

3. Consider the following criteria to serve as your guide in completing the given
task.

STORY-MAKING AND ROLE PLAYING CRITERIA

CRITERIA Percentage
Preparation 15%
Achievement of Objective 35%
Imagination and Creativity 30%
Presentation 20%
TOTAL 100%

KEY CONCEPTS
The best way to prevent diseases in the respiratory and circulatory systems is to
have a healthy lifestyle, which includes balanced diet, regular exercise, adequate rest,
proper hygiene, and avoiding vices such as cigarette smoking and alcohol drinking.
Circulatory and respiratory disease can easily be detected with regular health check-up
and physical screening.

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 The following activity that you will perform is a variation of a famous application
game, known as “Four Pics – One Word.” Use your analytical thinking in answering
each set of puzzles.

Activity 9

What’s the Word?

Objective:
 Infer how one’s lifestyle can affect the functioning of the respiratory and
circulatory systems

Procedure:
All four pictures in each given set depict negative ways of living. They are
connected by one common word that indicates the effect of one’s lifestyle on the
functioning of the respiratory and circulatory systems. The expected answers are
illnesses that are brought about by the negative lifestyles. Write your answers in the box
provided for each number.

1.

What’s the word?

A____A

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2.

What’s the word?

H_ _ _ _ _ _ _ _ _ _ N

3.

What’s the word?

A_ _ _ _ A

masslive.com

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Guide Questions:

Q26. What idea is common in each set of pictures?

______________________________________________________________________

Q27. What are the negative lifestyles that are depicted in the pictures?
______________________________________________________________________

Q28. How can lifestyle affect the functioning of the respiratory and circulatory systems?
______________________________________________________________________

Q29. How can these negative lifestyles be changed?

______________________________________________________________________

Q30. What might happen if a person goes on with a negative lifestyle such as what was
seen in the activity?
______________________________________________________________________

ENRICHMENT ACTIVITY

1. Compose a short poem about how one’s lifestyle can affect the functioning
of the respiratory and circulatory systems, and recite it in front of the class.

2. Cut out different examples of unhealthy lifestyles from old magazines or

newspapers, and create a collage out of the cut-outs on your notebook or journal.

KEY CONCEPTS
Several lifestyle choices can affect a person’s risk for developing respiratory and
circulatory diseases. Negative lifestyle weakens your system while healthy lifestyle leads
to complete wellness. Vices, stressful environments, and unhealthy eating habits can
cause various diseases, specifically of the respiratory and circulatory systems.

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Performance Task: Information
Dissemination Activity
Goal: Your objective is to present helpful information to the public about effective
ways of taking care of the respiratory and circulatory systems based on gathered
data. The challenge is how you will be able to lead the people to take action
rather than merely accepting the presented information. There are obstacles to
overcome such as the reluctance and preconceived notion of people against
changing their lifestyle to promote health.

Role: Suppose you work for an advertising company as a graphic artist and your
job is to create public informational materials. You are asked to disseminate
information to the public regarding a lifestyle that ensures healthy condition of the
respiratory and circulatory systems.

Audience: Your target individuals to receive the information that you will provide
are the people in your school community including all students, teachers, and
school officials. Parents and other persons who visit your school might also see
your work. Therefore, it is important that you convince them to consider the ways
of taking care of their bodies, specifically the circulatory and respiratory systems.

Situation: Upon gathering information from the school or local health workers,
you have found out that poor lifestyle affects the performance of the respiratory
and circulatory systems. Many people are unaware of this, so they simply
continue with their busy lifestyles, neglecting their health, and exploiting their
bodies. The challenge involves dealing with this by creating a poster that will stir
up the people’s consciousness in having a healthy lifestyle.

Product: Design a wall poster or placard that will make members of your
audience aware of how they can effectively take care of their respiratory and
circulatory systems. You may use any medium for your artwork.

Standards: You will be given three (3) days to conceptualize and execute your
ideas through poster-making. Once the product is finished, post it in a
conspicuous place such as the canteen where everyone can see it.

Your output will be assessed in accordance with the following rubric.

26
 Poster Making: Information Dissemination on How to Take Care of the
Respiratory and Circulatory Systems

RUBRIC

CATEGORY 4 3 2 1
Presentation The poster The poster The poster The poster does
clearly communicates indirectly not sufficiently
communicates some of the communicates communicate
the main idea important ideas the idea and any idea that
and strongly and slightly hardly promotes can promote
promotes promotes awareness awareness
awareness awareness
Creativity and All of the Most of the The graphics The graphics
Originality graphics used graphics used were made by were not made
on the poster on the poster the student but by the student.
reflect an reflect student were copied
exceptional ingenuity in from the
degree of their creation. designs or
student ideas of others.
ingenuity in
their creation.
Accuracy and All graphics in Most graphics Some graphics The graphics in
Relevance of the poster are in the poster are in the poster are the poster are
the Content accurate and accurate and accurate and neither accurate
related to the related to the related to the nor related to the
topic. topic. topic. topic.
Required The poster All required Few required Required
Elements includes all elements are elements are elements are
required included. included. missing.
elements as
well as
additional
information.

27
 Summary
 Air enters the body through the nose, nasal passages, and then through
windpipe or trachea, which divides into two branches, called bronchial tubes or
bronchi. The bronchi subdivide many times inside the lungs, forming hairlike
tubes called bronchioles. At the end of the bronchioles are tiny bubble-like
structures called alveoli.

 When you breathe in or inhale, the diaphragm muscle contracts. When you
breathe out, or exhale, the diaphragm muscle relaxes. The diaphragm helps
the air go in and out of the lungs.

 Air first enters your lungs and then into the left part of your heart. It is then
pumped by your heart into the bloodstream, all the way through your body.
Once it reaches the cells, oxygen processes the nutrients to release energy.
Carbon dioxide is the waste material given off during this process. The blood
delivers carbon dioxide into the right portion of your heart, from which it is
pumped to the lungs. Carbon dioxide leaves your body through the lungs when
you exhale.

 The heart is a hollow muscular organ, about the size of your fist, which is
located in the center of your chest between the lungs. It is a double pump that
pumps on the left and right sides. Each side is divided across into two
chambers. The top chamber is called the atrium. The bottom chamber is called
the ventricle. The valve acts as one-way door, allowing blood to flow either
forward into the next chamber, or out of the heart.

 Heart rate or pulse is the number of times your heart beats in a minute (BPM or
beats per minute). When you are resting, your heart rate slows down, as your
body does not need as much oxygen as it does when you exercise.

 Cigarette smoking harms nearly every organ in the body, causing many
illnesses and affecting health in general. The negative effects of smoking on the
circulatory system include increased heart rate and blood pressure, coronary
heart disease, arteriosclerosis, and vascular diseases. The respiratory diseases
caused by smoking are chronic bronchitis, emphysema, asthma, cough, colds,
tuberculosis, lung cancer, and other respiratory infections.

 The best way to prevent diseases in the respiratory and circulatory systems is
to have a healthy lifestyle, which includes balanced diet, regular exercise,
adequate rest, proper hygiene, and avoiding vices such as cigarette smoking

28
 and alcohol drinking. Circulatory and respiratory disease can easily be detected
with regular health check-up and physical screening.

Summative Assessment

Answer the following questions briefly.

1. The nutrients obtained from the food during digestion are supplied by the
circulatory system to the body. What does the circulatory system distribute to the
body as it works with the respiratory system?

______________________________________________________________

2. If solid and liquid wastes are removed from the body through defecation and
urination, what is released by the body as waste during respiration?

______________________________________________________________

3. What happens to the diaphragm when a person breathes in or inhales?

______________________________________________________________

4. Why is the human heart called a double pump?

______________________________________________________________

5. What will happen if oxygen is not transported by the blood to the different parts of
the body?

______________________________________________________________

6. Since the valves act as the doors of the heart, what might happen if these doors
do not close?

______________________________________________________________

29
 7. When we breathe in, we inhale many gases present in the air, including oxygen.
What do you think happens to the gases that are not needed by the body?

______________________________________________________________

8. You always hear and see the statement, “Government Warning: Cigarette
smoking is dangerous to your health.” How does cigarette smoking increase the
risk of developing cardiovascular diseases?

______________________________________________________________

9. How does singing from the diaphragm, instead of the throat, help improve the
voice quality of a singer?

______________________________________________________________

10. An old woman joined a kilometer-dash sprint and felt very exhausted afterwards.
How did the old woman’s activity affect her heart rate?
______________________________________________________________
UNIT 1 Suggested Time Allotment: 8 to 10 hrs

Module
2
Heredity: Inheritance and Variation

Overview

Non-Mendelian Patterns of Inheritance

In Grade 8, you learned that cells divide to produce new cells and meiosis is one of the
processes producing genetic variations in Mendelian patterns of inheritance. In Grade 9, you will
focus on describing the location of genes in chromosomes, explain the different patterns of non-
Mendelian inheritance and describe the molecular structure of the DNA.

30
 Gregor Mendel’s principles form the base for the understanding of heredity and
variation. Although Mendel’s work failed to discuss thoroughly the ‘factors’ or genes he
mentioned in his laws of inheritance, his findings prompted other scientists to probe further into
the mystery of heredity. Several researches were conducted after the rediscovery of Mendel’s
work.
Walter Sutton and Theodore Boveri became popular because they found the best
evidence that an inherited trait is determined by chromosomes. Chromosome Theory of
Inheritance explained that genes are in the chromosomes.
Mendelian laws of inheritance have important exceptions to them. For example, not all
genes show simple patterns of dominant and recessive alleles.
In this module, you are expected to:
1. Explain the different patterns of non-Mendelian inheritance
a. Identify characters whose inheritance does not conform with predicted outcomes
based on Mendel’s laws of inheritance;
b. Solve genetic problems related to incomplete dominance, codominance
multiple alleles and sex-linked traits.
c. Identify the law that was not strictly followed in the non-Mendelian inheritance
2. Describe the location of genes in chromosomes.
a. Explain the chromosomal basis of inheritance.
b. Identify the components of a DNA molecule
As you work on different activities in this module, you should be able to answer the following key
questions:

 How is non-Mendelian inheritance different from Mendel’s observations?

 What is the role of DNA in the transmission of traits?

Before you start with the module, be sure to answer the pre-assessment questions.
Pre-Assessment :
Answer briefly the following questions:
1. Pink four o’clock flowers are obtained from a cross between pure bred red flower plant
and white flower plant. What is the genotype of the pink flowers?
________________________________________________

31
 2. The structure of the DNA is actually in a double helix arrangement. The nitrogen bases
in each of the chain can only pair with specific bases, like adenine pairs only with
thymine and cytosine pairs only with guanine. If the left chain of a DNA molecule has the
nucleotide sequence CCGTAGGCC, what is the sequence of the right chain of the DNA
molecule?___________________________________________
3. Read the given problem.
In some aliens, one center horn (A) is codominant with two horns (B). If an alien inherits
both alleles (AB), then the alien has three horns. A recessive allele (O) results in an alien which
has no horns. Can you match the genotype to each of the pictures below? Write the genotype
and phenotype of the four aliens in the box provided.

1. 2. 3. 4.

Source: (image) www.biologycorner.com

In the Mendelian patterns of inheritance, the effects of the recessive gene are not
observed when the dominant gene is present. In this lesson, you will find out that certain
traits do not always follow the Mendelian principles of heredity.

1. Incomplete Dominance
In incomplete dominance, a heterozygote shows a phenotype that is intermediate
between the two homozygous phenotypes. Neither allele is dominant over the other.
An example of incomplete dominance is flower color in four o’clock plant, like those
shown in Figure 1. When a pure red-flowered four o’clock plant is crossed with a pure white-
flowered four o’clock plant, the offspring will produce neither red nor white flowers. Instead,
all flowers will be pink.
 Do you think the alleles blended to make pink?
In incomplete dominance, it is only the phenotype that is intermediate. The red and white
alleles remain separate and distinct. Half the gametes of the pink four o’clock carry the

32
 allele for red and half carry the allele for white. Therefore, the genotypic ratio also becomes
the phenotypic ratio.

Source: buffonescience9.wikispaces
Figure 1. Punnett square showing a cross between red and white four o’clock flowers

Now, work on this activity to help you understand better incomplete dominance.

Activity 1 Phenotypes and

Genotypes in Incomplete
Dominance
Objectives:
 Explain incomplete dominance pattern of inheritance
 Illustrate by means of Punnett square a cross involving incomplete dominance pattern of
inheritance.

Materials:
Activity sheets
Manila paper
Marking pen

33
Procedure:
1. Read the given problem:

In four o’clock plants, R is the allele for red color and W is allele for white
color. Two pink flowered four o’clock plants were crossed.

Show the possible outcome of the cross between two pink flowered four o’clock plants by using
the Punnett square.

2. Now, another cross was made involving a red

flowered four o’clock plant and a pink flowered four
o’clock plant.
3. Using the Punnett square again, show the possible outcome.
4. Show your Punnett square for problems 1 and 2 by writing it on a Manila paper.
5. Present and discuss your answers.

Guide Questions:
Q1. How many types of gametes will each parent produce in problem no. 1?_________
In problem no. 2? ___________
Q2. What is the phenotype of a heterozygous four o’clock flower?__________
Q3. What are the possible phenotypes of the offspring from the cross of the parental
plants in problem no. 1?_________________
In problem no. 2?_____________
Q4. What are the possible genotypes of the offspring from the cross of the parental
plants in problem no. 1?_________________
In problem no. 2?_____________

Key Concepts
Incomplete dominance is a form of intermediate inheritance in which one allele for a
specific trait is not completely dominant over the other allele. This results in a third
phenotype in which the expressed physical trait is a combination of the dominant
and recessive phenotypes.

34
 Now, that you are familiar with incomplete dominance, let us find out what happens when
one allele is not dominant over the other.

2. Codominance (adapted from Grade 8 Learner’s module –since non-Mendelian is not

included in the learning competency)
Another pattern of inheritance is codominance. This results when one allele is not
dominant over the other. The resulting heterozygotes exhibit the traits of both parents.
One example of codominance is the MN blood typing in humans. On the surface of our
red blood cells are proteins bound to sugar molecules, forming complexes called
antigens. One group of antigens are controlled by a pair of alleles, LM and LN. The
pairing of these alleles will determine the blood type of an individual, and there are three:
M, MN and N. Table 1 summarizes the genotypes and phenotypes of the MN blood
typing in humans.
Table 1 Human MN blood types and their genotypes.

Blood Types Genotype

M LMLM
MN LMLN
N LNLN

Note that in the heterozygote condition, both LM and LN alleles are expressed in that
the red blood cells will have the M and N antigens. Just like in incomplete dominance,
the genotypic ratio in codominance also becomes the phenotypic ratio.
Another good example of codominance is roan fur in cattle as shown in Figure 2.
Cattle can be red (RR = all red hairs), white (WW = all white hairs), or roan (RW = red &
white hairs together).

Source: www.biologycorner.com

35
 Figure 2 Codominance in cattle ( for illustrator/artist -Please include the colored picture of a
roan cow to show the appearance of red and white hair together)
You will work on the activity that demonstrates codominance of traits.

Activity 2 Mystery Bull

Objectives:
 List the genotypes of the bull and cow in the given problem
 Diagram and complete a Punnett square
 Give phenotypic percentages of the offspring

Materials: (by group)

Marking pen
Manila paper

Procedure:
1. Read the given problem:
Mang Marcelino owns purebred red cows. In his farm he noticed that after a
typhoon several months ago, all of the fences that separate his cattle from his
neighbor’s cattle were destroyed. During the time that the fences were down, three
bulls, one from each neighbor, mingled with his cows. For awhile, he thought that
none of the bulls found his cows, but over the months, he noticed that all of his cows
are pregnant. He suspected that one of the bulls is the father. Which bull is it? Help
Mang Marcelino look for the father by solving the given problem.

Determine the possible traits of the calves if :

 a red (RR) bull is mated with a red (RR) cow 1

 a red(RR) bull is mated with a white (WW) cow 2
 a roan(RW) is mated with a red(RR)cow 3

2. Illustrate your answers using a Punnett square.

36
 3. Write your answers on the Manila paper.
4. Present and discuss your answers.
Q5. Will you be able to trace the father of the calves?______________
What are the possible phenotypes of the calves for each
cow?________________________________________________
Q6. Do you think you will make Mang Marcelino happy about the result of
your investigation? _________________________________
Q7. How are you going to explain it to him? ________________________
Q8. How would you apply what you have learned to improve the breeds of livestock
in your area?
_____________________________________________________________
Q9. What possible suggestions can you give to animal breeders in your area?
Key Concepts

In codominance, both alleles are expressed equally in the phenotype of the

heterozygote. For example, red cows crossed with white cows will have
offspring that are roan cows. Roan refers to cows with red hair and white
blotches.

Many genes have multiple alleles. An example is ABO blood type in humans.

1. Multiple Alleles (adapted from Grade 8 Learner’s module –since non-Mendelian is

not included in the learning competency in Grade 8)

Sometimes, even if only two alleles control a trait, there may actually be more than
two types of alleles available. This will also lead to more than two phenotypes
expressed. Another blood group system in humans, the ABO system, is an example of
a character governed by multiple alleles. Three alleles are responsible for this blood
system: IA , IB, and i. The ABO blood type is determined by the presence or absence of
two antigens, A and B. Allele i does not code for an antigen. There are four possible
blood types as shown in Table 2.

Table 2. Human ABO blood types and their phenotypes.

Blood Types Genotypes
A IA IA , IA i
B IB IB , IB i
AB IA IB
O ii

37
 The IA and IB alleles are dominant over the i allele, which is always recessive.
However, when the IA and IB alleles are inherited together, both alleles are expressed
equally. This also makes IA and IB codominants of each other.
 What is your blood type? Do you know your blood type? What are your
parents’ blood types?

Activity 3 What’s your blood type?

Objective:
 Infer the unknown phenotypes of individuals on the basis of the known
phenotypes of their family members

Materials:
 Paper
 Pencil

Procedure:
A. Given the blood types of the mother and the child, identify the possible blood type of
the father.
Mother’s Blood Type Father’s Blood Type Child’s Blood Type
A A
B AB
AB B
O O

B. Show the possible alleles that can be found in each offspring and write the blood
type for each offspring.

Possible alleles from Father

A B O

38
 A

Possible alleles from

B
Mother

Use the table to answer the following questions, and list all possible blood types.

Q10. What blood type (or types) can be found in an offspring if a mother has type A

blood and the father has type B blood?________________________________

Q11. What blood type (or types) can be found in an offspring if a mother has type AB

blood and the father has type B blood?________________________________

Q12. What blood type (or types) can be found in an offspring if a mother has type O

blood and the father has type B blood?_________________________________

Key Concepts:
 In humans, there are four blood types (phenotypes): A, B, AB, O.
 Blood type is controlled by three alleles: A, B, O.
 O is recessive, two O alleles must be present for a person to have type O blood.
 A and B are codominant. If a person receives an A allele and a B allele, their blood
type is type AB.

39
 The inheritance of some characters does not strictly follow Mendel’s Law of Independent
Assortment. There are many traits that are inherited together more frequently. For example, the
expression of certain traits depends on whether one is male or female. Apparently, the
expression of the traits is determined by or related to one’s sex.

Sex Chromosomes and Sex Determination

Humans have 46 chromosomes in each cell. Observation of the human body cells
shows 23 pairs of chromosomes for both males and females. Twenty- two pairs are somatic
chromosomes. The 23rd pair consists of sex chromosomes. Human males and some other
male organisms, such as other mammals and fruit flies, have non-identical sex chromosomes
(XY). Females have identical (XX) sex chromosomes.

 How is sex determined and inherited?

Let us study gamete formation based on the sex chromosomes. You will observe in
Figure 3 that all egg cells receive an X chromosome; while half of the sperm cells receive X
chromosomes and the other half receive Y chromosomes.

Male
Female
XY
Sex chromosomes XX

Meiosis

X X X Y
Gametes

40
 Figure 3. Gamete formation involving only sex chromosomes

Female Male
Parent XY
XX

Gametes
X X X Y

Fertilization

Zygote
Female Male Female
XX XY XX

Male
XY

41
 Figure 4. Sex determination

If an egg is fertilized by a sperm with a Y chromosome, as shown in Figure 4, the

offspring is male. When an egg is fertilized by a sperm carrying an X chromosome, the offspring
is female. Note that there is a 50 percent chance of having a male or female offspring. The
greater the number of offspring, the greater is the chance of getting the expected 1:1 ratio of
male and female.

Activity 4 Boy or Girl ?

Objective:
 Discuss how sex in humans is determined

Materials:
Activity sheets

Pen

Paper

Procedure:
1. Draw a Punnett square which shows the inheritance of the sex chromosomes.
Represent the female sex chromosomes with XX and the male sex chromosomes with
XY.

42
Guide Questions:
Q 13. What will be the sex of a child produced when an egg is fertilized by a sperm that

has a Y chromosome?

_______________________________________________

Q 14. What type of sperm must fertilize an egg to result in a female

child?_________________________________________________

Q 15. Based on this Punnett Square, what percent of children would you expect to be

male?____________________________________________________

Q 16. Which sex chromosome is present in both male and

female?_____________________________________________________

Q 17. Infer which sex chromosomes determines a person’s sex.

_______________________________________________

18. What are the other factors that may influence the expression of

human sexuality?.________________________________________

______________________________________________________

Key Concepts

 Males have 44 body chromosomes and two sex chromosomes X and Y. The
males determine the sex of their children. Females have 44 body
chromosomes and two sex chromosomes, both X. The total number in each
cell of an individual is 46. These chromosomes contain the genes, which are
the factors
This section of heredity.
discusses three kinds of sex-related inheritance, namely, sex-limited, sex-
influenced and sex-linked.

Sex-Linked Genes

43
 Genes located on the X chromosomes are called X-linked genes. Genes on the Y
chromosomes are called Y-linked genes. An example of an X-linked trait in humans is
hemophilia. A person suffering from hemophilia could die from loss of blood even from a small
wound because the blood either clots very slowly or does not clot at all. Another example of an
X-linked trait is color blindness. To illustrate the inheritance of an X-linked trait, we will use color
blindness in our discussion. Let us study Table 3. The X chromosome with the gene for color
blindness is represented as XC, while the one without is represented as X.

Table 3 Genotypes and phenotypes of color blindness in humans

Genotype Phenotype
1. X X Normal female
2. X XC Normal female, carrier of the gene
3. XC XC Color- blind female
4. XY Normal male
5. XC Y Color-blind male

Can you identify the genotype of the female who is color-blind? Notice that for a female
to become color-blind, she must be homozygous (X C XC) for the color-blind genes. The trait is,
therefore, recessive in females. If a female has only one X chromosome with the allele for color
blindness, she becomes normal but can pass on the trait to her offspring. She is therefore a
carrier of the trait. Since males have only one X chromosome, the gene for color blindness
when present in the male, will always be expressed because it does not have an allele to hide
or prevent its expression. Thus, the male will be color- blind. This is the reason why color
blindness is more common in males than in females.
Figure 5 is an example of a Y-linked trait, hypertrichosis pinnae auris, a genetic
disorder in humans that causes hairy ears. Since the trait is found in the Y chromosome, then
only males can have the trait. A father who has the condition will pass it on to all his sons, and
they, in turn, will pass it
on to their own sons.

44
 Figure 5. Sex-linked Genes Source: www.mun.ca

Activity 5 When Gender Matters

Objective:
 Solve problems related to sex-linked traits.

Materials:
Activity sheets

Procedure:
1. Read the given problem:
A. Color-blindness is a recessive, sex-linked disorder in humans. A color-blind man has
a child with a woman who is a carrier of the disorder.
KEY: X = normal vision Xc = color-blindness
2. Illustrate using a Punnett square the probability of having children who will have normal
vision and children who will be color-blind.

Guide Questions:
Q19. What is the genotype of the male?__________________________________
Q20. What is the genotype of the female?________________________________
Q21. What is the chance that the child will be color-blind?_____________________
Q22. What is the chance that a daughter will be color-blind? ___________________
Q23. What is the chance that a son will be color-blind?________________________

Key Concepts
 Sex-linked traits are inherited through the X chromosomes.
 Males have only one X chromosome. Thus, if they inherit the affected X,
they will have the disorder.
45  Females have two X chromosomes. Therefore, they can inherit/carry the
trait without being affected if it acts in a recessive manner.
 Have you seen a bald man? What about a bald woman? It appears that gender matters
for the other kinds of traits as well.
Sex-Limited Traits
Sex-limited traits are generally autosomal, which means that they are not found on the
X or Y chromosomes. The genes for these traits behave exactly the same way that any
autosomal gene behaves. The difference here comes in the expression of the genes in the
phenotype of the individual. Sex-limited traits are expressed in only one gender. In cattle, for
instance, lactation is expressed in females but never in males. Both male and female cattle
however possess a gene pair for lactation. The gene for lactation (L) is dominant over the non-
lactating gene(l). Table 4 shows the genotypes and phenotypes of the gene for lactation. These
genes are carried by both males and females, but it is only expressed in females. Have you
noticed that in female cattle, if at least one gene pair is for lactation (L), the female produces
milk? In male cattle, it does not matter if they possess one or two genes for lactation. They
never produce milk.

Table 4. Expression of Lactation in Cattle

Female Genotypes Female Phenotypes
XXLL Female lactating
XXLl Female lactating
XXII Female not lactating
Male Genotypes Male Phenotypes
XYLL Male not lactating
XYLI Male not lactating
XYII Male not lactating
Source: Functional Biology Modular Approach, Second edition

Guide Questions:
Q24. Can you give other examples of sex-limited traits in animals?
____________________________________________________________

Sex-Influenced Traits

46
 Sex-influenced traits are also autosomal, meaning that their genes are not carried on
the sex chromosomes. Again, what makes these traits unusual is the way they are expressed
phenotypically. In this case, the difference is in the ways the two genders express the genes.
One classic example of a sex-influenced trait is pattern baldness in humans, though
the condition is not restricted to males. This gene has two alleles, “bald” and “non-bald”. The
behaviors of the products of these genes are highly influenced by the hormones in the
individual, particularly by the hormone testosterone. All humans have testosterone, but males
have much higher levels of this hormone than females do. The result is that, in males, the
baldness allele behaves like a dominant allele, while in females it behaves like a recessive
allele. Study Table 5 which shows the pattern of expression for baldness.

Table 5. Expression of Pattern Baldness in Humans

Male Genotypes Male Phenotypes
XYBB Male bald
XYBb Male bald
XYbb Male nonbald
Female Genotypes Female Phenotypes
XXBB Female bald
XXBb Female nonbald
XXbb Female nonbald
Source: Functional Biology Modular Approach, Second edition

Guide questions:
Q25. Predict the genotypic and phenotypic ratios in the offspring if the mother is bald and the
father is not bald. Perform a cross using a Punnett square.
___________________________________________________________________
Q26. In what way are sex-limited and sex-influenced characters similar?
___________________________________________________________________
Q27. What is the main difference between sex-limited and sex-influenced traits?
__________________________________________________________________

If you look at the heterozygous gene pair for baldness (Bb), males express baldness, while
females do not. Baldness may be expressed in females but it occurs more frequently in males.
Such trait is sex-influenced because of a substance that is not produced equally in males and
females.

47
 Key Concepts
 Sex-limited traits are those that are expressed exclusively in one sex.

 Sex-influenced traits are expressed in both sexes but more frequently in one
than in the other sex.

Try this (optional)

Solve the following problems:

1. Hemophilia is a disease caused by a gene found on the X chromosome. Therefore, it is
referred to as a sex-linked disease. The recessive allele causes the disease. A man
with hemophilia marries a woman that is homozygous dominant for the trait.
Make a key for the trait. XH=____________Xh = _____________

A. Illustrate using a Punnett square the probability that their children will have the
disease.

Q28. Identify the genotype of the male?_________ female?_____________

Q29. Will any of their children have the disease?______________________
Q30. Predict the probabilities of their children having the disease._________________

48
 2. Blood type is determined by the presence or absence of two antigens – antigen A and
antigen B. The body’s ability to produce antigens is a trait that is inherited. Using the
information about inheritance of blood type, answer the given problem:
 A father of four children has blood type A. The mother has blood type O.
Q31. Predict the possible blood types of their children.________________________
Q32. Explain why two of their children have blood type A while the other two have blood
type O.________________________________________________________

DNA is a macromolecule that forms a double helix structure in the cells (mostly in
the nuclei and mitochondria) of living organism. The DNA molecule is considered the
genetic material of all living cells. It is present in bacteria, protists, fungi, plants and
animals. DNA is responsible for determining the specific characteristics of an organism.

DNA: The Genetic Material

We’ve talked a lot so far about chromosomes and the inherited trait that genes produce.
But what are genes? How do they work? After the discovery of the Chromosome Theory of
Inheritance, many questions remained unanswered.
 Of what material are genes made?
 How does the genetic material produce the characteristics of an organism?
 How is the genetic code passed from parents to offspring?
If you recall your lesson in Grade 8, all living things contain what we call the genetic
material that serves as the set of instructions that direct the activities and function of the cell.
The genetic materials, also known as the deoxyribonucleic acid or DNA are passed on from
one generation to the next to ensure continuity of life.
Scientists now know that the genetic material is DNA (Deoxyribonucleic acid). Modern
research techniques helped scientists to answer many questions about DNA and heredity.
The work of earlier scientists gave Watson and Crick a lot of information about DNA. By the
end of the 1940’s, scientists had found that DNA consists of long strands of nucleotides.
Each nucleotide contains a pentose sugar called deoxyribose, a phosphate group, and one
of the four compounds called nitrogenous bases. Look at Figure 5. What are the
components of the nucleotide?

phosphate

base

49
 deoxyribose sugar

Figure 5. Structure of a nucleotide

This activity will introduce you to DNA. DNA is a complex molecule that is found in
almost all living organisms. You will be able to manipulate the nucleotides (basic building
blocks) of DNA and get a feel of how the molecule is produced.

You will perform an activity that will help you understand some important concepts in
DNA structure.

Activity 6 DNA Modeling

Objectives:
 Identify the components of a DNA molecule
 Construct a model of a molecule of DNA

Materials:
Cutouts of basic subunits of DNA
Crayons
Scissors
Tape or glue

50
Procedure:
1. Color and cut out all of the units needed to make the nucleotides from the handout provided
on page 55. Color code phosphate (brown), deoxyribose sugar (black) and nitrogeneous
bases ; Adenine = yellow, Guanine = green, Thymine = blue, Cytosine = red.
2. Using the small squares and stars as guide, line up the phosphate and sugars. Attach the bases to
the sugar using the circle as guide following the sequence to form a row from top to bottom.
Thymine
Adenine
Cytosine
Guanine
Adenine
Cytosine
Let this arrangement represent the left half of the DNA molecule.
Q33. What are the common parts of a nucleotide?________________________

Q34. What is the one part of the nucleotide that differs among the other different
nucleotides?____________________________________________
Q35. List the different kinds of nitrogen bases___________________________

A molecule of deoxyribose joins with phosphate and anyone of the four bases to form a
chemical compound called a nucleotide. A nucleotide is named for the base that joins with the
deoxyribose. For example, if thymine attaches to deoxyribose, the molecule is called a thymine
nucleotide.

3. Complete the right side of the DNA molecule by matching the bases of the other nucleotides.
It may be necessary to turn molecules upside down in order to make them fit.

Q36. What is the pairing arrangement of the nitrogenous bases?

___________pairs with ______________ and __________pairs with ___________.
Q37. Are there always going to be an equal number of adenine and thymine nucleotides in
molecule?___ Why?_________________________________________
Q37. Are there always going to be an equal number of guanine and cytosine nucleotides in

51
 a molecule? ___ Why?______________________________________

The structure of the DNA is actually in a double helix arrangement as shown in Figure 6.
Double helix means that the long two chains of nucleotides are arranged in a spiral like twisted
ladder.

Figure 6. Double helix structure of DNA

Source: http://ircamera.as.arizona.edu/NatSci102/NatSci102/text/nucleicacid1.htm
Q38. The sides of the ladder are made up of alternating ___________and_______________
molecules. The steps (or rungs) of the ladder are made up of ____________ held together by
hydrogen bonds.

Key Concepts

DNA is composed of chains of nucleotides built on a sugar and phosphate backbone and
wrapped around each other in the form of a double helix. The backbone supports four
bases: guanine, cytosine, adenine, and thymine. Guanine and cytosine are
complementary, always appearing opposite each other on the helix, as are adenine and
thymine. This is critical in the reproduction of the genetic material, as it allows a strand to
divide and copy itself, since it only needs half of the material in the helix to duplicate
successfully.

Summary

52
  Many characteristics have more complex inheritance patterns than those studied
by Mendel. They are complicated by factors such as codominance, incomplete
dominance, multiple alleles, and sex-linked traits.
 Incomplete dominance occurs when the phenotype of the offspring is
somewhere in between the phenotypes of both parents; a completely dominant
allele does not occur.
 Codominance occurs when both alleles are expressed equally in the phenotype
of the heterozygote.
 Many genes have multiple (more than two) alleles. An example is ABO blood
type in humans. There are three common alleles for the gene that controls this
characteristic. The alleles IA and IB are dominant over i.
 In humans, XX chromosomes determine femaleness and XY determine
maleness.
 A sex-linked trait is on the X chromosome. Females have two X chromosomes;
they can inherit or carry the trait without being affected if it acts in a recessive
manner.
 Sex-limited traits are those that are expressed exclusively in one sex.
 Sex-influenced traits are expressed in both sexes but more frequently in one
than in the other sex.
 Genes are located in the chromosomes.
 DNA contains the information needed to form and control the physical make-up
and chemical processes of an organism.
 DNA is a double-stranded helix made up of repeating units of nucleotides.
 A nucleotide is composed of the following: sugar and phosphate molecules, and
nitrogeneous bases. The base can either be adenine, guanine, thymine, and
cytosine.

Glossary

 Allele – a different form of a gene that controls a certain trait.

53
  Codominance – two dominant alleles of a contrasting pair fully expressed at the same
time in the heterozygous individual.
 Incomplete dominance - occurs when the phenotype of the offspring is somewhere in
between the phenotypes of both parents; a completely dominant allele does not occur.
 Multiple Alleles – when more than two alleles control the inheritance of a character.
 Sex-influenced traits – are expressed in both sexes but more frequently in one sex
than in the other.
 Sex-limited traits that are expressed exclusively in one sex of the species.
 Sex-linked traits – traits that are controlled by genes located on the same sex
chromosome.
 DNA - deoxyribonucleic acid
 Punnett square – the method by which one can determine the possible genotypes and
phenotypes when two parents are crossed
 Antigen - A substance that when introduced into the body stimulates the production of an
antibody
 Gamete - are reproductive cells that unite during sexual reproduction to form a new cell called
a zygote.

Summative Assessment (for end of module assessment)

Answer the following questions.

1. Complete the Punnet square for a cross between a homozygous red-flowered

snapdragon (RR) and a homozygous white-flowered snapdragon (rr). Give the ratio for
the phenotype and the genotype.

Key

Genotypic Ratio: _____________

RR – red F1

rr – white Phenotypic Ratio ________________

Rr – pink

54
 2. What happens to the phenotype of the heterozygotes when traits are inherited in an
incomplete dominance pattern?

3. Complete the Punnet Square for a cross between two F 1 plants (rr). Give the phenotypic
ratio for the F2 generation.

F2

Phenotypic ratio ___________________

4. What is the name of the inheritance pattern in which both alleles are expressed equally?

5. Complete the Punnet square for a cross between a black chicken (BB) and a white
chicken (WW). Give the phenotype of the offspring in the F1 generation.
Key

BB – black

WW – white F1

BW – checkered

Phenotype ___________________________________________________

Summative test (for end of the unit)

1. One chain of a DNA molecule has a nucleotide sequence C, C, G, C, T. What is the sequence of the
nucleotides on its partner chain?_____________________________
2. Predict the phenotypic ratios of offspring when a homozygous white cow is crossed with a roan bull.
Illustrate using a Punnett square.

3. In fruit flies, humans and other mammals, sex is

determined by an X-Y system. However, many organisms do not have the X-Y system of sex
determination. For example, birds have a Z-W system. Male birds are ZZ, whereas females are ZW.
In chickens, barred feathers (Z) are dominant over nonbarred feathers (Zb).

55
 a. Draw a Punnett square that shows the results of a cross between a barred female and a nonbarred male.
b. What is the probability that the offspring will be:
i. Barred females? __________
ii. Nonbarred females? __________
iii. Barred males? __________
iv. Nonbarred males? __________
4. Identify the components of the DNA nucleotide.

________

B. ________

C. ________

5. Using the following information mentioned, complete the following table.

Blood type Possible Gene Pairs
A
B
AB
O

DNA Model Template

56
Figure 7 Basic Subunits of DNA
Reference:

DNA Paper Model Activity

http://www.karenmayes.com/pages/dna.pdf

57
 UNIT 1 Suggested Time Allotment: 4 to 5 hrs

Module
3
Biodiversity and Evolution

Overview

Causes of Species Extinction

In Grade 8, you learned about the concept of species, classification of organisms
using the hierarchical taxonomic system and the advantage of high biodiversity in
maintaining the stability of an ecosystem. In Grade 9, you will explain the importance of
biodiversity, find out how changes in the environment may affect species extinction and
relate species extinction to the failure of populations of organisms to adapt to abrupt
changes in the environment.
In any ecosystem, organisms need a balanced environment. A balanced
ecosystem is one in which all living and nonliving things are interacting successfully. If
any part of the ecosystem is disturbed, other parts will also be affected.
What happens to a community when its species diversity is reduced? Does loss
of biodiversity affect an ecosystem’s ability to sustain the species that remain or to
perform certain functions that may contribute to the needs of that ecosystem? This
module will help you find answers to these questions.
In this module, you are expected to:
1. Relate species extinction to the failure of populations of organisms to adapt to
abrupt changes in the environment,
 Explain the importance of biological diversity.
 Find out how changes in the environment can affect species extinction.
 Distinguish environmental changes that may result in the loss of the species.
2. Make a multimedia presentation of a timeline of extinction of representative
microorganisms, plants, and animals

58
 Key Questions:
 What causes species extinction?
 How can changes in the environment affect the continued survival of the
species?

Now read carefully the questions and give your best answer. These will help your
teacher determine the knowledge you have for this topic.

Pre-Assessment:

Taking Animals for Profit Introduced species

Hunting and Trapping Destruction of habitat

Overharvesting Pollution

A. Photo Quiz: The words in the box are some of the causes of species
extinction. Look at the pictures below and identify which cause of
extinction matches each group of pictures.

1.

2.

59
 3.

4.

5.

60
 B. The map below shows the population distribution of fish, water bugs, frogs and
water lily plants in a pond.

Key:

= fish = frogs

= water bug = water lily

1. Which species has the largest

population in the community?

___________________________

____________________________
2. What factors might influence a
change in the population?
_________________

61
Different parts of the ecosystem interact with one another. Changes to one part affect
other parts. When all the members of a species die, that species’ place in the
ecosystem is gone forever. In this module you will study the various threats that are
considered causes of the loss of biodiversity.

Figure 1 Tubbataha Reef Figure 2 Coconut Plantation

Study Figures 1 and 2. Picture yourself swimming and diving in Tubbataha Reef Marine
Park, where very high densities of marine species are found. What organisms are in
Figure 1? How many different kinds of organisms do you think you will see? Now,
imagine yourself standing in a coconut plantation. Which species do you think
dominates this area? The Tubbataha Reef Marine Park has many populations. You can
see hundreds of different species of organisms, whereas in a coconut plantation, only
one species dominates. A population is a group of living things within a certain area
that are all of the same species.

62
 Several different populations may be found in a community. A population of one
kind may affect a population of another kind within the community. A jungle has a
greater amount of biological diversity, or biodiversity, than a cornfield. Biodiversity
refers to the variety of life in the area. In a jungle community, some populations, such as
ants, fungi, and ferns, can be very large in number. Other populations such as tigers
and snakes have fewer members. Why do you think population sizes vary among
organisms?

Now work on the activity to find out the amount of biodiversity and species
distribution in a community.

Activity 1 Index of Diversity

Objective:

 Measure species distribution using mathematical way of expressing the

amount of biodiversity and species distribution in a community.

Materials:

Pen
Paper
Procedure:

1. This is an outdoor activity. Go to the area designated by your teacher.

2. Record the number of different species of trees present in the area. (It is not
necessary to know their names, just make sure that they differ by species.)
Record this number in your data table.
DATA TABLE

Number of species

Number of runs

Number of trees

63
 3. Go to the designated area again. This time, make a list of the trees by assigning
each a number as you walk by it.
4. Place an X under Tree 1 on your list. If tree 2 is the same species as Tree 1,
mark another X under Tree 1. Continue to mark an X under the trees as long as
the species is the same as the previous one.
5. When a different species is observed, mark an O under that tree on your list.
Continue to mark an O if the next tree is the same species as the previous. If the
next tree is different, mark an X.
6. Record in your data table:
a. The number of “runs”. Runs are represented by a group of similar symbols in
a row. Example – XXXXOOXO would be 4 runs (XXXX – 1 run, OO – 1 run,
X – 1 run, O – 1 run).
b. The total number of trees counted.
7. Calculate the Index of Diversity (I.D.) using the given formula:
Index of diversity = Number of species x number of runs
Number of trees

Guide Questions:
Q 1. Compare how your tree I.D. would be different in a vacant lot than that in
a grass lawn. Explain your answer. _____________________
______________________________________________________________
Q 2. If humans were concerned about biological diversity, would it be best to have
a low or high I.D. for a particular environment? Explain your answer.
______________________________________________________________

Key Concepts

 Population pertains to the number of organisms of the same species

living in a certain place.

 Biodiversity refers to the variety of life in an area.

 Communities with many different species (a high index of diversity)

will be able to withstand environmental changes better than
communities with only a few species (a low index of diversity).
64
In a balanced ecosystem, organisms need a balanced environment. A change in
population sizes may be due to factors affecting the environment. Why is it that
populations do not increase without end?

Figure 3 Park reserve in Calauit, Palawan

Look at Figure 3. This is an area in Calauit, Palawan, which is set aside as a park
preserve, and no hunting is allowed in the park. A number of animals like giraffe and
zebra are placed in the area. There are plenty of plants to serve as food for the giraffe
and zebra population. The herd of giraffe and zebra are assumed to be healthy and
begin to multiply faster than expected. Predict what will happen if the giraffe and zebra
population continues to increase in the park area.
You will work on the next activity to help you understand changes in population,
factors affecting population growth and size, and learn about the needs and
characteristics of a population.

65
Activity 2 Measuring Population
Density
Objective:

 Determine the pattern of population distribution using mathematical

formula

 Compare the distribution patterns of the different populations.

Materials:
Ruler
Pencil & Paper Figure 4.

Procedure:

1. Study the three patterns of

population distribution in Figure
4.

2. Using the given formula for

118cm
computing population density,
calculate the density of each
population.

Density = number of individuals

Size of area
3. Count the total number for
each population. Record the 20 cm
Figure 4.
number in the table.
Bermuda grass Clover Lilies

4. On a sheet of paper, prepare a table to record the data for population density.

Table 1 Population Density

Population name Number of organisms Density

66
 6. Calculate the density of each population. Record it in the table.

Guide Questions:
Q 3. Compare the distribution patterns of the three populations.
___________________________________________________________
Q 4. Which population has the greatest density?_______________________
Q 5. Infer from recorded data from the possible causes for the differences in the
population density.
Q 6. What conditions could change the density of any of the population.
_______________________________________________________________
Q 7. Describe how a population’s density can be used to learn about the needs and
characteristics of that population.
_____________________________________

Populations can be of the same size, but they may have different densities. When we
consider the number of individuals per unit area, we are referring to the density of the
population. Differences in population density in any community may be attributed to
many factors. Population sizes change when new members move into the ecosystem.
They decrease when members move out of an ecosystem. The birth rate and death
rates can also affect a population’s size. Anything that limits the size of a population like
certain environmental conditions are called limiting factors. Limiting factors keep a
population from increasing in size and help balance an ecosystem. Examples of limiting
factors are the availability of food, water, and living conditions. Light, temperature and
soil nutrients are also limiting factors because they help determine the types of
organisms that can live in an ecosystem. The maximum population size an environment
can support is called its carrying capacity. If the population size rises above the
carrying capacity, organisms die because they cannot meet all their needs.

Q 8. How are limiting factors related to population density?

__________________________________________________________

67
 Key Concepts:

 Population sizes vary among organisms. They change with the

number of births and when they move into an ecosystem. They
also change when members die or move out of an ecosystem.

 Limiting factors are environmental conditions that keep a

population from increasing in size and help balance ecosystems.

 The carrying capacity is affected by changes in the environment.

Life depends on life. Animals cannot exist without green plants. Living things
create niches for other living things. But what happens if the living conditions of these
organisms are not ideal for their survival? What do you think are the major causes of
species extinction?

Work on the next activity which demonstrates the probable causes of species
extinction.

Activity 3 Endangered but not Extinct…yet

Objective:
 Demonstrate, using a simulation activity, that habitat destruction can contribute
to species extinction.
Materials:
Box of toothpicks
Stopwatch/wristwatch
Pencil & paper
Flour for marking areas in the lawn
Procedure:
1. Create teams of seven members.

68
 2. Designate two students as the “Hunters”, two students as the “Timers”, two
students as the “Counters “ and one student as the Leader.
3. Get your copy of the Extinction Simulation Data Table handout from your teacher.
4. Go to the area in the school grounds designated by your teacher. Using flour
draw out a circle measuring about 20 feet wide.
5. In the circle, scatter 100 toothpicks as randomly as possible. These are the
“toothpick grasshoppers”.
6. The Leader gives instructions to the students assigned as the following:
 Hunters: “Catch” by picking up as many toothpick grasshoppers as they can
 Timers: Set the time for two minutes for the Hunters to collect the toothpick
grasshoppers.
 Counters: Determine how many toothpick grasshoppers have been caught and
calculate the number of toothpick grasshoppers remaining in the circle. Record
this information in the Extinction Simulation Data Table handout.
7. Begin the activity. The Leader sees to it that the students perform their assigned
task for the activity.
8. After the first round, put an additional toothpick grasshopper into the circle for
every pair of toothpick grasshoppers remaining. This simulates reproduction.
9. Rotate roles and repeat the activity a second time and record the data in the
handout.
10. After the second round, rotate roles once again and repeat the activity for a third
time and record the data in the handout.
11. Draw a line or bar graph of the number of toothpick grasshoppers in the grass at
the end of the round.
Guide Questions:
Q 9. What happened to the toothpick grasshoppers over time?
__________________________________________________________
Q 10 What factors might account for differences in the graphs and /or total
number of toothpick grasshoppers in each group?
________________________________________________________
Q 11. In nature, what environmental factors might account for differences in the

69
 total number of grasshoppers?
__________________________________________________________
Q 12. What effects do you think will habitat reduction have on the toothpick
grasshoppers’ population?______________________________________
__________________________________________________________
Q 13. Suggest a method for testing your hypothesis in Q 12.
___________________________________________________________
___________________________________________________________

When a species’ population becomes so low that only a few remain, the species
is considered endangered will possibly become extinct. In the Philippines, some
terrestrial species like the tamaraw in Mindoro, mouse deer in Palawan, Philippine deer,
Monkey-eating eagle, and aquatic species like the dugong found in Negros, Batangas,
and Leyte are in danger of extinction.
Sometimes, there is a particular species that declines so fast that it becomes
endangered and is said to be threatened. In a study conducted by field biologists on
population size and distribution of Philippine fauna, they reported that as of 1991, 89
species of birds, 44 species of mammals, and eight species of reptiles are
internationally recognized as threatened. These include also the Philippine Eagle or
Monkey-eating Eagle in the list of Philippine Endangered Species. (Source: cf. Rabago,
L. et.al. Functional Biology:Modular Approch. 2 nd ed)
Extinction is the disappearance of a species when the last of its members die.
Changes to habitats can threaten organisms with extinction. As populations of people
increase, the impact of their growth and development is altering the face of the Earth
and pushing many other species to the brink of extinction.

Key Concepts:

 Extinction occurs when the last member of that species dies.

 When the population of a species begins declining rapidly, the species

is said to be a threatened species.

70  A species is endangered when its population has become so low that it

is possible of becoming extinct.

 Human actions have resulted in habitat loss and degradation that have
 Many changes take place in the communities. You may have noticed that the
natural vegetation in the area has been cleared. Concrete structures and increasing
populations of people and other organisms gradually take over the area. Perhaps some
areas were destroyed by natural disasters or by human activities. Just as vegetation
changes, animal populations also change. These may have major effects on the
ecosystem causing replacement of communities or development of a new environment.
The next part of the module is basically a discussion of local and global
environmental issues that contributed to species extinction.

Activity 5 Making Predictions

Objective:
o Determine differences between two hypothetical islands

Materials:
Paper & pencil

Procedure:
1. Imagine that you and your friends are being sent to explore two islands. The
islands are very similar in size, age, and location. But one has human
population and the other does not have.
2. Predict what you will see in each island.
3. Tabulate your predictions as shown below.

Island A Island B

1. 1.

2. 2.

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Guide Questions:

Q 14. What did you predict you will see in each island?________________________
______________________________________________________________
Q 15. How would you explain the differences that you will see in each island?
______________________________________________________________

Have you eaten? Did you turn on an electric light, ride a tricycle or jeepney, or use a
computer today? When you do any of these activities, you use one or more natural
resources. Natural resources are materials in the environment that people use to carry
on with their lives. But are you using these natural resources wisely? Will the time come
when these materials will no longer be available to you? You would probably have the
same question in mind.
Many of the changes that man has done to the environment were made by
accident. If you examine your predictions in the activity, you probably listed them in the
column meant for the island inhabited by human population. Land would be cleared for
housing and farming. These might decrease plant and animal populations, and some
pollution and other environmental problems would result.
You probably need to know more about some of the local and global
environmental issues/problems that are also affecting your community.

 Deforestation
One of the country’s environmental problems is the rapid rate at which trees are cut
down. Did you encounter the same problem in your community? In the Philippines, the
major causes of deforestation are:

 Kaingin farming
 Illegal logging
 Conversion of agricultural lands to housing projects
 Forest fires
 Typhoons

72
 Figure 5 Kaingin farming Figure 6 Forest hit by typhoon

As a consequence of cutting down trees, the following effects could take place:

 Soil erosion
 Floods
 Decrease in wildlife resources that will eventually lead to extinction

As human population gets bigger,

 Wildlife Depletion huge space is needed for shelter, for
growing crops, and for industries.
Deforestation is one of the major causes
of the disappearance of wildlife species.
What happens to animal populations
that are driven away from their natural
habitat? If they cannot find enough
space, many will die or become extinct.
Some species may become
endangered, or in the verge of
becoming extinct. In other cases, some
animals may be threatened, referring to
species that are close to being
Figure 7 Monkey-eating Eagle endangered. Figures 7, 8 and 9 are
some examples of endangered species.

73
 Figure 8 Tarsier Figure 9 Dugong

 Water Pollution
A major problem in lakes, rivers and ponds is eutrophication. It happens when the
concentration of organic nutrients that comes from domestic garbage and thrown in
bodies of water, increases rapidly. one of the effects of water pollution. It is supposed
to be a slow process, but man’s activities hasten it up. Figure 10 shows the causes and
stages of eutrophication in a lake.

Figure 10 Eutrophication

74
 Another effect of water pollution is mass death of fish, or ‘fish kill’. Have you read
articles from the newspapers about ‘fish kill’ in Manila Bay or some other places? Have
you seen such an event in your area?
A ‘fish kill’ usually happens when there is an increase in concentration of organic
nutrients in bodies of water. This condition causes algal bloom and growth of aquatic
plants. When the algae die, they sink to the bottom and the process of decomposition
proceeds. This process uses up oxygen and as a result, aquatic animals die due to lack
of oxygen.
Bodies of water are also polluted with toxic wastes, untreated sewage, and
fertilizer run-offs from farm lands. One class of dangerous chemicals present in water is
PCB (polychlorinated biphenyl). PCBs are toxic wastes produced in the making of
paints, inks and electrical insulators. Figure 11 shows what happens in the food chain
when PCB is present.
At each level of the food chain, the amount of PCB in each organism increases.
They are unable to excrete PCB from their bodies.
Through the process of biological magnification, the PCB becomes concentrated
in the body tissues of water organisms. Biological magnification is the buildup of
pollutants in organisms at higher trophic levels in a food chain. Fish living in
contaminated ecosystems contain builtup high concentration of PCB as shown in
Figure 11. The fish were not killed by the chemicals, but they stored them in their
tissues. As the salmon feeds on the smaller fish, it took in the PCB in their bodies. Like
the smaller fish, the salmon was not killed by the PCB. It stored the PCB in its tissues.
The concentration of PCB in the salmon has rise to 5,000 times the concentration of
PCB in the water in which it fed.

75
 has

feeds

Figure 11 PCB dumped in lakes (Please redraw)

Other pollutants found in water are heavy metals such as lead, mercury, and
cadium. These metals come from factories that dump their wastes into rivers or lakes.
 Air Pollution
Do you know that cars are one of the major contributors to air pollution? Pollutants
can enter the air as gases, liquids, or solids. Cars burn fuel and produce harmful gases–
carbon dioxide, nitrogen oxides, and hydrocarbons. Figure 12 shows the harmful
pollutants present in the air.

Figure 12 Air Pollution

76
 In Metro Manila where a great volume of cars travel each day, smog blankets the
area, nitrogen oxides and hydrocarbons from car exhausts react with water vapour or
dust particles and produce new irritating chemicals.
Carbon dioxide acts like a blanket over the Earth, holding in the heat that would
otherwise radiate back into space. The trapping of heat by gases in the earth’s
atmosphere is called greenhouse effect.
The greenhouse effect is a natural process. But as carbon dioxide in the
atmosphere increases, greenhouse effect also intensifies–this will lead to global
warming. Global warming is an increase in the earth’s temperature from the rapid
buildup of carbon dioxide and other gases. This, in turn, could change the world climate
patterns.
Are there factories in your area? Factories and power plants that burn coal are
also major contributors to air pollution. Coal contains sulfur. When coal burns, sulfur
combines with oxygen in the air to form sulfur dioxide, with choking odor. Power plants
also burn coal to give off particulates into the air. Particulates are tiny particles of soot,
dust, and smoke. These particulates block sunlight and get into your lungs when you
breathe. Do you see smog and smell such foul odor and often wonder where it comes
from? Well, your place might be a victim of air pollution from the factories nearby.

 Destruction of Coastal Resources

Do you live near coastal areas? Do you remember the times when you and your
friends went to the seashore to gather seashells or played with some corals or, perhaps,
played hide and seek among mangrove trees?

Coral reefs and coastal mangrove forests in the Philippines serve as breeding
grounds and nurseries of marine fishes. But due to man’s activities, coastal areas are
getting destroyed through the years. Some of these activities include the following:

 Deforestation, agricultural activities, and mining activities

 Dynamite fishing and muro-ami
 Coastal areas’ conversion to beach resorts, residential areas
 Overharvesting

77
 Figure 13 Destruction of coral reefs

Figure 14 Damaged mangrove areas

Figure 15 Dynamite Fishing

 Acid Precipitation
Acid precipitation is commonly known as acid rain. Rainwater is normally acidic,
because carbon dioxide is normally present. Other pollutants, mostly sulfur and nitrogen
oxides, make rainwater even more acidic, with a pH of 5.6 or lower. Emissions from
factories and from exhaust of motor vehicles are some examples of pollutants.
Acid rain can be harmful to living things. It causes yellowing of leaves of trees and
cause leaves to fall. Examine Figure 16. It summarizes the effect of acid rain.

78
 Figure 16 Acid precipitation

Along with nutrients being lost through direct leaching from leaves and no
movement of nutrients in forest litter (leaves, stems, and fruits), nutrients can be lost
from the soil. Acid water flowing through the soil can exchange acidic hydrogen ions for
essential plant nutrient ions such as calcium, magnesium, and potassium. If these
nutrients migrate beneath the rooting zone, they become unavailable to tree roots.

Human activities and overpopulation have caused most of the environmental

problems nowadays. People are beginning to realize that the way they interact with the
environment must change to ensure the survival of all living things. This is one big
challenge to maintain the resources needed for survival while ensuring that they will still
be available in the future. This is a practice called sustainable development. This
means that a sustainable society should live under the carrying capacity of the
environment. This means that the rate at which society uses renewable resources does
not exceed the rate at which the resources are generated.

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Key Concepts :

 The principal causes of deforestation are illegal logging, kaingin farming,

forest fires, and conversion of agricultural lands to housing projects and
typhoons.

 The effects of deforestation include soil erosion, floods and depletion of

wildlife resources.
 The major cause of wildlife extinction is the loss of habitat.
 Coral reef destruction is caused by dynamite fishing and muro-ami, while
mangrove destruction is caused by overharvesting and conversion of the
area into other uses.
 In eutrophication, nutrients are washed away from the land to enrich
bodies of water. It causes excessive growth of aquatic plants and algae
and results in algal bloom, which eventually die and decompose. The
process depletes the oxygen dissolved in water, causing fish and other
aquatic organisms to die.
 Acid rain is a result of air pollution mostly from factories and motor
vehicles.
 Sustainable development means that a society should live under the
carrying capacity of the environment.

Performance Task
Now that you have understood the causes of species extinction, you will
try to make a multimedia presentation of a timeline of extinction of representative
microorganisms, plants, and animals.
Your teacher will give you detailed instructions on this task.

80
Summary
 Population is a group of organisms of the same species living in a certain place.

 Biodiversity refers to the variety of life in an area.

 Communities with many different species (a high index of diversity) will be able
to withstand environmental changes better than communities with only a few
species (a low index of diversity).

 Population sizes vary among organisms. They change with the number of births
and when they move into an ecosystem. They also change when members die
or move out of an ecosystem.

 Limiting factors are environmental conditions that keep a population from

increasing in size and help balance ecosystems.

 The carrying capacity is affected by changes in the environment.

 Extinction occurs when the last member of a species dies.

 When the population of a species begins declining rapidly, the species is said to
be a threatened species.

 A species is in endangered whenits population is so low that it is nearly extinct.

 Human actions have resulted in habitat loss and degradation that has
accelerated the rate of extinction.

 The principal causes of deforestation are illegal logging, kaingin farming, forest
fires, and conversion of agricultural lands to housing projects, and typhoon.
 The effects of deforestation include soil erosion, floods, and depletion of wildlife
resources.
 The major cause of wildlife depletion is the loss of habitat.
 Coral reef destruction is caused by dynamite fishing and muro-ami, while
mangrove destruction is caused by overharvesting and conversion of the area
into other uses.
 In eutrophication, nutrients are washed away from the land to enrich bodies of
water. It causes excessive growth of aquatic plants and algae and results in
algal bloom, which eventually die and decompose. The process depletes the
oxygen dissolved in water, causing fish and other aquatic organisms to die.

81
  Acid rain is a result of air pollution mostly from factories and motor vehicles.
 Sustainable development means that a society should live under the carrying
capacity of the environment.
GLOSSARY
Species A group of organisms that have certain characteristics in
common and are able to interbreed.
Biodiversity refers to the variety of life in an area.
Population the total number of organisms of the same species
inhabiting a place at the same time.
Population density the number of individuals in an area
Limiting factor environmental conditions that keep a population from over
increasing in size and thus help balance ecosystems
Carrying capacity number of organisms of one species that an environment
can support.
Endangered species a species in which the number of individuals falls so low that
extinction is possible
Threatened species species that have rapidly decreasing numbers of individuals
Deforestation removing or clearing of a forest to include the cutting of all
trees, mostly for agricultural or urban use
Eutrophication the process by which a body of water becomes enriched in
dissolved nutrients (such as phosphates) that stimulate the
growth of aquatic plant, life usually resulting in the depletion
of dissolved oxygen
PCB (polychlorinated biphenyl) toxic wastes produced in the
making of paints, inks and electrical insulators
Acid rain broad term referring to a mixture of wet and dry deposition
(deposited material) from the atmosphere containing higher
than normal amounts of nitric and sulfuric acids.

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Summative Test
I. Answer briefly the following questions in your answer sheet:
1. If the population species of a given area is doubled, what effect would this have on the
resources of the community?
2. In a population, limiting factors and population density are often related. Suppose that
the population density of plant seedlings in an area is very high, explain how limiting
factors may affect population density.
3. In a farm, soy beans were the only crop that that was planted on several hectares of
land. A farmer noticed that a fungus was growing all over the soy bean fields. Predict
what might eventually happen to the soybeans and the fungus.
4. How is forest ecosystem affected when trees are cut down?
5. What is the main cause of extinction in plant and animal species?
II. Work on the following problems:
1. Suppose 60 ants live in a 4 sq m plot of grass. What would be the population density of
the ants? What would the population density be if 100 ants live in an 8 sq m plot of
grass?
2. If 40 carabaos live in a 1 ½ sq m area, what is their population density per sq. km. ?
3. How many monkeys would have to live in a ¾ sq. km. area to have the same population
density as the carabao?
III. Choose the best answer that completes each sentence.
1. Pollutants dumped into the rivers and streams eventually find their way to (a. the ocean
b. the atmosphere c. groundwater supplies)
2. The average temperature of the earth’s atmosphere may rise as a result of (a. the
greenhouse effect b. water pollution c. garbage dumping)
3. Many (a. non-renewable b. alternative c. expensive) energy sources are being
developed to replace fossil fuels.
4. Some endangered species of plants in tropical rain forests may be sources of (a. fossil
fuel b. medicine c. hazardous waste)
5. Humans are using (a. fewer b. better c. more) natural resources than they did 100 years
ago.

83
 Suggested Time Allotment: 15 hrs.

Unit 1
Module

4 ECOSYSTEM: Life Energy

Overview

In module 3, you have learned how changes in the environment may affect
species extinction. It helps you understand how to prevent extinction of organisms in an
ecosystem.

In this module, you will learn that all organisms need energy to sustain life. Your
study will focus on how organisms obtain energy from food and how organisms produce
energy.

In order to sustain life, all organisms require energy, but not all of them can use
light energy directly for life activities. To provide the energy needed by all organisms,
plants and other chlorophyll-bearing organisms capture the energy of sunlight and
convert it into chemical energy stored in the food. When people and other heterotrophic
organisms eat food from producers and consumers, chemical energy stored from food
is transferred to their bodies. Do you know how these processes are being done by
our body and by other living organisms?

What are expected of you to learn?

1. Differentiate basic features and importance of photosynthesis and respiration.

a) Describe the parts of organelles involved in photosynthesis and cellular
respiration.
b) Describe the process of food making by plants.
c) Describe how stored energy from food is changed to chemical energy for cell
use.
d) Identify the factors that affect the rate of photosynthesis and cellular respiration.
2. Design and conduct an investigation to provide evidence that plants can
manufacture their own food.

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Key questions for this module

How do plants manufacture their own food?

What are the factors that affect the rate of photosynthesis?
How do cells convert stored energy in food into chemical energy?
How do materials and energy flow in the ecosystem?

Now you have to read and answer the questions that follow in the best way you can.
Your answers will give the teacher the necessary information on what you already know
and those topics that need to be given more emphasis.

Pre Assessment:

1. Plants make food by absorbing water and carbon dioxide. Which of the following
substances is the origin of oxygen released as gas by green plants during
photosynthesis?
a. water c. carbon dioxide
b. sugar d. ribulose-1,5-biphosphate
2. Oxygen and carbon dioxide are gases that cycle out in the ecosystem. Which of
the following gases is important to photosynthesis?
a. ozone gas b. water vapor c. oxygen d. carbon dioxide
3. Plants are considered as food makers. In which of the following cell organelles
does photosynthesis occur?
a. ribosome b. chlorophyll c. chloroplast d. mitochondrion
4. The light-dependent reaction of photosynthesis must come first before the light
independent reaction because its products are important to the fixation of carbon
dioxide. Which of the following is/are the product/s of the light–dependent
reaction?
a. ADP only b. NADPH only c. ATP only d. NADPH and ATP
5. Plants are very unique among other organisms due to their capability to trap
sunlight and make their own food. Which of the following enables plants to trap
energy from the sun?
a. epidermis b. chloroplast c. cuticle d. chlorophyll
6. All organisms get energy from food to perform different life processes. This is
done in the cells by breaking down sugar molecules into chemical energy. Which
of the following cell organelles is associated with the production of chemical
energy?
a. chloroplast b. mitochondrion c. endoplasmic reticulum d. nucleus

85
 7. Pyruvate is the product of glycolysis. If there is no oxygen available to cells of the
human body, what becomes of pyruvate?
a. alcohol b. lactic acid c. CO2 d. a and c
8. If you did not eat for three days, where did your cell get the glucose for ATP
production?
a. blood sugar c. glycogen present in the muscle
b. glycogen in the liver d. protein in the blood
9. How many molecule/s of carbon dioxide is/are released from one pyruvic acid
molecule being oxidized?
a. 1 b. 3 c. 2 d. 4
10. During the synthesis of ATP, what is the direction of hydrogen flow?
a. from matrix to intermembrane space
b. from intermembrane space to matrix
c. from matrix of mitochondrion to cytoplasm
d. from cytoplasm to matrix of mitochondrion

Photosynthesis

Plants are great food providers. Why do you think they are called great food
providers? As you go through the activities in this module, you will understand how
plants provide food and help to make the flow of energy in the ecosystem possible.

You will understand how each plant structure helps in the process of food
making, as well as the factors that may affect the rate of food production done by plants.

Photosynthesis is a process of food making done by plants and other autotrophic

organisms. The presence of chlorophyll enables these organisms to make their own
food. Autotrophic organisms require light energy, carbon dioxide (CO 2), and water
(H2O) to make food (sugar).

In plants, photosynthesis primarily takes place in the leaves and little or none in
stems depending on the presence of chlorophyll. The typical parts of the leaves
include the upper and lower epidermis, mesophyll spongy layer, vascular bundles,
and stomates. The upper and lower epidermis protects the leaves and has nothing
to do with photosynthetic processes. Mesophyll has the most number of chloroplasts
that contain chlorophyll. They are important in trapping light energy from the sun.
Vascular bundles - phloem and xylem serve as transporting vessels of manufactured
food and water. Carbon dioxide and oxygen were collected in the spongy layer and
enters and exits the leaf through the stomata.

86
 The parts of a chloroplast include the outer and inner membranes,
intermembrane space, stroma and thylakoids stacked in grana. The chlorophyll is
built into the membranes of the thylakoids. Chlorophyll absorbs white light but it
looks green because white light consists of three primary colors: red, blue, and
green. Only red and blue light is absorbed thus making these colors unavailable to
be seen by our eyes while the green light is reflected which makes the chlorophyll
looks green. However, it is the energy from red light and blue light that are absorbed
and will be used in photosynthesis. The green light that we can see is not absorbed
by the plant and thus, cannot be used in photosynthesis.

There are two stages of photosynthesis: (a) Light-dependent Reaction and (b)
Calvin Cycle (dark reaction). Light-dependent reaction happens in the presence of
light. It occurs in the thylakoid membrane and converts light energy to chemical
energy. Water-one of the raw materials of photosynthesis-is utilized during this stage
and facilitates the formation of free electrons and oxygen. The energy harvested
during this stage is stored in the form of ATP (Adenosine Triphosphate) and NADPH(
Nicotinamide Adenine Dinucleotide Phosphate Hydrogen). These products will be
needed in the next stage to complete photosynthetic process.

Calvin Cycle (dark reaction) is a light-independent phase that takes place in the
stroma and converts Carbon dioxide (CO 2) into sugar. This stage does not directly
need light but needs the products of light reaction. This is why it occurs immediately
after the light-dependent phase.

The chemical reaction for photosynthesis is:

Carbon Dioxide + Water Chlorop Glucose + Oxygen

hyll
(CO2) (H2O) Sunli (C6H12O6) (O2)
ght

What do you think are the plant structures that enable a plant to make food? Try
the activities below to find out.

Listen to your teacher for further instructions on how you can complete the task
in the activities that follow.

87
 Activity
What
1 are the structures involved in the food making
process in plants?

You will go to different learning stations by group and will visit some websites
found on the activity sheets provided by your teacher. These websites contain
information about the plant structures and processes involved in photosynthesis. As you
visit the websites in different learning stations you must answer the questions.

Learning station 1: Plant Structure for Photosynthesis

Label the parts of a chloroplast and the internal structure of a leaf. Write your answer
in the box.

A. Internal structure of a leaf

B. Chloroplast

Source: http://dendro.cnre.vt.edu/forestbiology/photosynthesis.swf
88
Learning Station 2: Identify the raw materials and end products of photosynthesis.

Complete the table below: Write the raw materials and products of
photosynthesis.

Raw Materials Products

_____________________________ _____________________________
_____________________________ _____________________________
_____________________________ _____________________________
_____________________________ _____________________________

Learning Station 3: Understanding the Process of Food making

After watching the video clip on photosynthesis, make a concept map of

the entire process by filling up the figures with the processes involved, raw
materials used, and end products of the entire process of food making.

89
 KEY CONCEPTS:

Plants have green pigments called chlorophyll stored in the chloroplast. This pigment
Plants have green pigments called chlorophyll stored in the chloroplast. This pigment
aids in capturing light energy from the sun that enables plants to change it into chemical
aids in capturing light energy from the sun that enables plants to change it into chemical
energy stored in the food. This process is called photosynthesis.
energy stored in the food. This process is called photosynthesis.
Carbon Dioxide + Water Glucose + Oxygen
Carbon Dioxide + Water Glucose + Oxygen
(CO2) (H2O)(C6H12O6) (O2) Sunlight
(CO2) (H2O)(C6H12O6) (O2)
Chlorophyll

Now that you understand photosynthesis, try to look and examine the structure
that enables the entrance and exit of gases in the leaf.

Activity

2
Investigating the Leaf Stomata

Objectives:
 Identify the stomata
 Describe the function of the stomata

Materials:
Leaf of Rheo discolor (boat lily) Clear nail polish
Glass slide Clear tape
Microscope

Procedure:

1. Paint a thick patch of clear nail polish on the lower surface of the leaf.
2. Allow the nail polish to dry completely.
3. Put a clear tape to the dried nail polished patch.
4. Gently peel the nail polished patch by pulling the corner of the clear tape.
This will serve as your leaf impression for microscopic observation.
5. Tape your leaf impression on a clean glass slide.
6. Observe the leaf impression under low power
objective of the microscope. Have you seen similar
structures as shown in Figure1?
Q1. Draw and label the stomata as seen under
the microscope. Which do you think are the
stomata? Figure 1: Stomata
Source:
http://www.flickr.com/photos/ajc1/8642458098/
90
KEY CONCEPTS:

Stomata are found on the lower surface of the leaf that allows the entrance of carbon
dioxide needed for photosynthesis. They also serve as exit point for the oxygen produced
during photosynthesis.

Are you excited to know more about photosynthesis? This time you will conduct
investigations that will show evidences that plants are really capable of making food.

Activity

3
Evidence of Photosynthesis

3A. To show that oxygen is produced by photosynthesis (Santan leaf can be

used if Elodea or Hydrilla is not available)

Materials:
Test tube water available plant sample

Procedure:

1. Place a fresh mature Santan leaf or Elodea or Hydrilla inside a test

tube. Add water to the test tube to cover the leaf or plant.
2. Leave the setup for about 3 to 5 minutes at room temperature
(29°C).

3. Observe the set-up.

Q2. What did you see on the leaf/plant? Figure 2: Sample set-up
_________________________________________________________.

Q3. Did you see any bubbles in the set-up?

_________________________________________________________

Q4. What do these bubbles indicate?

___________________________________________________________

91
 3B. To show that sugar is produced by photosynthesis

Materials:
Tincture of iodine Medicine dropper Wire gauge
Denatured alcohol Beaker Box of matches
Water bath Petri dish Fresh leaf of mayana
Alcohol lamp Tripod

Procedure:
1. Get a coleus leaf (mayana).
2. Remove the leaf color by boiling it in alcohol. To do this, follow the
steps below:
A. Fill the beaker (3/4 of its capacity) with water.
Let it boil. See Figure 3 for the sample set-up.
B. While waiting for the water to boil. Get a leaf
sample and place it on a test tube. Pour
denatured alcohol into the test tube, until the
leaf has been submerged. See Figure 3 for
the sample setup. Figure 3

C. When the water in the beaker boils, place the test tube with leaf
and alcohol in it. Let the water
boil for another three minutes or
until all the color of the leaf has
been extracted. See Figure 4 for
the sample setup.

Figure 4
3. Remove the test tube from the beaker. Then, get the leaf out of the test
tube.
4. Rinse the leaf with water, and then place it on a petri dish.
5. Put drops of iodine, until the leaf has been soaked.
6. Observe the leaf. If the color of the leaf turns to bluish black, it
indicates the presence of starch. No change in color indicates
absence of starch.

Q5. What can you infer from your observation?

_______________________________________________

3C. To show the effect of light on the rate of photosynthesis

Materials:
2 – 250 mL Beakers 2 test tubes scotch tape

92
 2 Funnels 2 Santan leaf or twigs of Hydrilla or Elodea
500 mL water used carbon paper

Procedure:
1. Make two setups similar to Figure 5.
2. Take 2-3 pcs. of small mature Santan leaves or
sprigs of healthy hydrilla and place them in a glass
funnel.
3. Invert the funnel in a beaker of water.
4. Invert a test tube full of water over the stem of the
funnel.
Figure 5: Sample set-up
5. Leave one of the setups in sunlight for three
minutes. At the same time, cover the other setup with a carbon paper in
a shaded area or cabinet.
6. Count the number of bubbles every 30 seconds and record it in the
observation table.

Do not insert the glowing splinter

Cauti without the teacher’s supervision
on
Optional: Remove the test tube carefully and insert a glowing splinter deep into it.
The splinter burns brightly. It indicates that oxygen is the gas collected in the test
tube.

Observation Table:

No. of Bubbles Produced

Time (seconds)
Exposed leaf Covered leaf
30
60
90
120
150
180
210

93
 Q6. Which setup produced more bubbles?
_____________________________________________________________
Q7. What do the bubbles indicate?
_____________________________________________________________
Q8. What gas is collected by the downward displacement of water in the test
tube?
____________________________________________________________
Q9. What happens to the number of bubbles as time passed?
_____________________________________________________________
Q10. How did you know that photosynthesis has taken place?
_____________________________________________________________
Q11. How does the amount of light affect the rate of photosynthesis?
_____________________________________________________________

3D. To show that carbon dioxide is needed in photosynthesis

(adapted from DepEd NSTIC Science II, Exercise 9, pages 20-22)

1. Testing for the presence of carbon dioxide

Materials:
4 Test tubes Drinking straw
4 Rubber stoppers lime water
2 Graduated cylinder

Procedure:

a) Label the test tubes A and B.

b) Measure 5 mL of lime water using a graduated cylinder and pour into
test tube A and test tube B.
c) Use a straw to blow air into test tube A, as shown in
Figure 6.
d) Cover it immediately with a rubber stopper. (Note that
exhaled air contains 3-4% carbon dioxide.)
e) Cover test tube B with rubber stopper
f) Shake both test tubes very well. Figure 6. Student
Photo credit: taken from blowing air into the
DepEd-NSTIC Manual test tube

Q12. What happened to the contents of the two test tubes?

94
 Write your observations in the table below.

Table1.

Setup Observation Possible Explanation

Test tube A (exhaled
with air)
Test tube B

2. Photosynthesis and carbon dioxide

Materials:
Small fresh leaves drinking straw
Water 2 Test tubes
Limewater 2 Rubber stoppers
Test tube rack
Procedures:

a) Prepare two test tubes; label them

test tube C and test tube D.

Photo Credit: Maricel Peña-SJDMNHS

Figure 7a. Test tubes C and D

b) With the use of a drinking straw, blow air into test tube C.
c) Insert two to three small leaves into the test tubes gently. Don’t
compress the leaves because they won’t be able to absorb adequate
carbon dioxide.
d) Cover both test tubes with a rubber stopper. See
Figure 7b.
e) Place the two test tubes on a test tube rack. And
put them under sunlight for 20 minutes.
f) After 20 minutes, get back the two test tubes and
bring them back to your working area.
g) Add 5 mL of lime water to each test tube and
cover with rubber stopper. Figure 7b. Sample Set-up
h) Shake well. Observe what happens to the Photo Credit: Maricel
contents of Peña-SJDMNHS
the two test
tubes.

95
 Write your observation on Table 2.

Table 2.

SetUp Observation Possible Explanation

Setup C

Setup D

Carbon dioxide is one of the important materials to enable plants to produce food.
After investigating the evidences that plants are photosynthetic organisms,
the next thing that you will do is to conduct another experiment that will show the
factors affecting the rate of photosynthesis. This will tell you how you can speed
up the process of food making and how it can affect the quantity and quality of
harvests.

3E. To show the effect of the varying amount of chlorophyll in the rate of
photosynthesis.

Materials:
1 fresh coleus leaf (mayana) Alcohol lamp
Denatured alcohol Beaker
Petri dish Wire gauze
Tripod Test tube
Medicine dropper Tincture of iodine

Procedure:
a) Get a variegated fresh coleus leaf (mayana) as shown
in Figure 8.
b) Draw the leaf. Shade the green parts. Label it Leaf A.
c) Remove the chlorophyll from the leaf by boiling it in
alcohol. To do this, follow the steps below. Figure 8. Mayana
Leaf
1. Fill the beaker with (3/4 of its capacity) with water.
Let it boil.
2. While waiting for the water to boil, get the leaf sample,
then place it in a test tube.
3. Pour alcohol in the test tube until the leaf has been Fig
ure
completely soaked as shown in Figure 9. 9

96
 4. When the water in the beaker boils, place the test tube in it. Let the
water boil for another three minutes or until all the colors of the leaf
have been extracted as shown in Figure 10.

Keep the alcohol away

Cautio
from the fire!
n

Figure
10
Q19. What changes did you observe?
____________________________________________________
Q20. What do you think caused the changes?
d) Using a test tube holder, remove the test tube from the beaker using. Then
____________________________________________________
get the leaf out of the test tube.
e) Rinse the leaf with water and place it on a petri dish.
Q21. What happened to the leaf after boiling?
__________________________________________________________
Q22. What can you infer from your observation?______________________
_____________________________________________________________
f) To test for the presence of starch, put drops of iodine until the leaf has been
soaked.
g) Observe the leaf. Draw the leaf and shade the bluish black area. Label it Leaf
B.
h) Compare your drawings of leaf A and leaf B.
Q23. Which part of the leaf is shaded?___________________
Q24. Which part of the leaf produced more starch?____________
Q25. How does the presence of green pigment affect the production of
starch? ____________________________________________________

KEY CONCEPTS:

The factors that affect the rate of photosynthesis are temperature, carbon
dioxide, water, and light. Providing the plant with the right amount of these
materials will ensure good quality and quantity of the harvest.

Cellular Respiration
All heterotrophic organisms including man, depend directly or indirectly on plants
and other photosynthetic organisms for food. Why do we need food? Organisms need

97
 food as the main source of energy. All organisms need energy to perform essential life
processes.

The food must be digested to simple forms such as glucose, amino acids, and
triglycerides. These are then transported to the cells. The immediate energy source of
the cells is glucose. Glucose inside the cell is broken down to release the stored energy.
This stored energy is harvested in the form of adenosine triphosphate (ATP). ATP is a
high-energy molecule needed by working cells.

Glycolysis

In glycolysis, the 6-carbon sugar, glucose, is broken down into two molecules of a 3-
carbon molecule called pyruvate. This change is accompanied by a net gain of 2 ATP
molecules and 2 NADH molecules.

Krebs Cycle

The Krebs Cycle occurs in the mitochondrial matrix and generates a pool of
chemical energy (ATP, NADH, and FADH2) from the
oxidation of pyruvate, the end product of glycolysis.

Pyruvate is transported into the mitochondria and loses

carbon dioxide to form acetyl-CoA, a 2-carbon molecule.
When acetyl-CoA is oxidized to carbon dioxide in the
Krebs cycle, chemical energy is released and captured in
the form of NADH, FADH2, and ATP.
Source:
http://www.hartnell.edu/tutorials
/biology/cellularrespiration.html
Electron Transport Chain

The electron transport chain allows

the release of the large amount of
chemical energy stored in reduced
NAD+ (NADH) and reduced FAD
(FADH2). The energy released is
captured in the form of ATP (3 ATP per
NADH and 2 ATP per FADH2).

Source:
http://www.hartnell.edu/tutorials/biology/cellularrespiration.html

98
 The electron transport chain (ETC) consists of a series of molecules, mostly
proteins, embedded in the inner mitochondrial membrane. This phase of cellular
respiration produces the greatest number of chemical energy in the form of ATP.

In the following activities, you will learn how the chemical energy of "food"
molecules is released and partially captured in the form of ATP (Adenosine
Triphosphate). You should learn first the part of the cell where ATP is produced.

Activity

4
The Power House!

Mitochondria are membrane-enclosed organelles distributed through the

cytoplasm of most eukaryotic cells. Their main function is the conversion of the potential
energy of food molecules into ATP. This organelle has important parts. An outer
membrane encloses the entire structure that contains many complexes of integral
membrane proteins that form openings. A variety of molecules and ions move in and out
of the mitochondrion through the openings. An inner membrane encloses a fluid-filled
matrix. This membrane contains five complexes of integral proteins such as:

 NADH dehydrogenase
 succinate dehydrogenase
 cytochrome c reductase (the cytochrome b-c1complex)
 cytochrome c oxidase
 ATP synthase

99
 Task: Describe each part of the
mitochondrion.

1. Eg. Cristae are the inner folded

membrane of the mitochondrion.

4. _________________________________
_________________________________
_________________________________
_________________________________
3. _________________________________
_________________________________
2. 1 _________________________________
.
_________________________________

KEY CONCEPTS:

Mitochondrion is considered as the power house of the cell. It plays an important role
in the breakdown of food molecules to release the stored energy in the form of ATP
(Adenosine Triphosphate).

Activity

5
Let Us ReCharge!

In this activity, you will learn the basic concept of how your cells release the
energy from the food you eat. Thus, you will understand how your eating habits and
daily activities affect the production and storage of energy of your body cells.

B. Understanding Glycolysis
Wait for further instructions to be given by your teacher.
Look at the diagram below and answer the questions that follow.

GLYCOLY
SIS
+ A
Gl Pyru
100 T
vate
uc P
os
e
 Guide Questions:

Q26. Which of the terms found in the diagram is considered a process?

_________________________________________________________
Q27. In which part of the cell does the process take place?
_________________________________________________________
Q28. What is the raw material?
_________________________________________________________
Q29. What are the products?
_________________________________________________________
Based on the diagram shown above, briefly describe the first step of
cellular respiration, emphasizing the location, raw materials needed and the end
products.

___________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________.

Use the task checklist below as your guide in describing the first metabolic
process of cellular respiration.

Task Checklist

Category

Content:
 States the raw materials and products of glycolysis
 Tells specifically the location in the cell where it takes
place.
Organization of data:
The ideas are presented in the right order, beginning with where
the process takes place, the raw materials used, up to the
processes involved in the formation of end products.
Spelling:
All words are spelled correctly .

101
 C. Let us go round and round..
You have understood and identified the raw material and end
products of Glycolysis. This time you will see the importance of the end
products of Glycolysis in the next stage, the KREBS CYCLE.

Your task is to arrange the following events in the Krebs Cycle in

proper sequence. Base your answer on the diagram. Assign numbers
1-7 in the space provided to indicate the correct sequence of events;
then rewrite them in a paragraph form.

_____ A. In a series of steps, the hydrogen and high energy electrons are
removed from the 2-carbon molecule.

_____ B. The 2-carbon molecule enters the cycle and joins a 4-carbon molecule.

_____ C. One ATP is formed.

_____ D. Two carbon dioxide are released.

_____ E. Three NAD+ are converted to 3 NADH and 3 H+.

_____ F. At the end of the cycle, nothing remains of the original glucose molecule.

_____ G. One FAD is converted into 1 FADH2.

___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

D. Pump it out!
You will watch a short video clip about oxidative phosphorylation or
electron transport chain, the final stage of cellular respiration. After

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 viewing the clip, answer the following questions. The animation of
electron transport chain can be viewed on the link below.

http://www.hartnell.edu/tutorials/biology/cellularrespiration.html

Q30. How will you describe the flow of electrons?

________________________________________________________
Q31. What do you think is the importance of NADH and FADH 2 in the
process?_______________________________________________
Q32. What is the final acceptor of the electron in the process?
________________________________________________________
Q33. What compound is formed when the electron combines with the
last acceptor? ___________________________________________

The electrons in NADH and FADH2 flow through a series of electron transport
The electrons in NADH and FADH2 flow through a series of electron transport
acceptors. The flow of electrons and H+ results in ATP formation. The last electron
acceptors. The flow of electrons and H+ results in ATP formation. The last electron
(hydrogen ions) combine with the last acceptor (oxygen) to form water.
(hydrogen ions) combine with the last acceptor (oxygen) to form water.
Glucose + Oxygen Carbon dioxide + Water + ATP
Glucose + Oxygen Carbon dioxide + Water + ATP
(C6H12O6) + (O2) (CO2) (H2O)
(C6H12O6) + (O2) (CO2) (H2O)

Activity

6
Comparing Photosynthesis and Respiration

There is recycling of materials through the chloroplast and mitochondrion.

Study the diagram below.

Light Chemical
energy Energy
Oxyg
en
Sug
ar

Chloroplas Mitochondri
103 t on

Carbon
 Wat
er

Table 2. Comparing Photosynthesis and Respiration

Basis of Comparison Photosynthesis Respiration

1. Cell structure involved
2. Starting materials/raw
materials
3. End product
4. Energy requirement

Materials are recycled through the processes of photosynthesis in the chloroplast and respiration in
the mitochondrion. However, the flow of energy is one-way.

Performance Task:

Now you have understood how energy from the sun is captured and converted to
life energy. This time, you will try to provide possible solutions to a community problem
or issue on food production. Most communities in urban areas depend mostly on the
supply of the crops from rural areas. What you need to do is to provide urban
communities with insights on how they can build small urban gardens in their homes.
You will apply what you have learned in photosynthesis.

Each group may develop a material such as brochure, multimedia presentation, a

facebook page, or a web page that contains tips and information on how to put up an
urban garden for crops suited for homes with limited space for planting.

Your teacher will give you detailed instructions on this task. Use the rubric as
your guide in planning, doing, and completing the task which will be provided to you by
your teacher. Your teacher will also give you a progress checklist form to help you keep
track of and monitor your progress.

Summary

 Through the process of photosynthesis, plants and other chlorophyll-bearing

organisms produce food for themselves.

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  In photosynthesis, plants capture light energy and convert it into chemical energy
stored in food.
 The summary equation for photosynthesis is as follows:
sunlight

Carbon dioxide + water glucose + oxygen

chlorophyll
 Photosynthesis occurs in the chloroplast found in the leaves of plants.
 Essentially, the two major stages in photosynthesis are:
o Light reaction phase
o Calvin Cycle
 Improved farming practices enhance photosynthesis that result in good harvest.
 Cellular respiration occurs in the mitochondria of the cells.
 Organisms release stored energy in food through the process of respiration.
 Respiration breaks down glucose into carbon dioxide, water and energy (ATP) in
the presence of oxygen.
 The summary equation of respiration is as follows:
Glucose + oxygen carbon dioxide + water + ATP
 The breakdown of glucose involves three major steps: glycolysis, Krebs cycle;
electron transport chain

SUMMATIVE TEST:
Choose the letter of the best answer. Write your answer on your answer sheet.

1. A farmer is experiencing a problem in growing his crops. Most of the leaves of the
crops are turning yellow. Which of the following will likely result from the yellowing of
the leaves of the crops?
a. It will increase the production of food.
b. It will decrease the production of food.
c. The production of food will remain the same.
d. None of the above.
2. Abby wants to know if leaves are capable of making food during nighttime. Which of
the following experimental design should Abby do to get an accurate answer to her
question?
a. Put one potted plant in a very dark place over night and test for the presence
of starch.
b. Cover the plant with paper bag overnight and test for the presence of starch.
c. Put one potted plant under the sun and the other in a shaded area for two
hours and test for the presence of starch.

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 d. Cover one leaf of a potted plant with carbon paper for two hours and test for
the presence of starch.
3. Which of the following materials are cycled out by the chloroplast and
mitochondrion?
a. Carbon dioxide, water, oxygen, and ATP
b. Carbon dioxide, water, sugar and oxygen
c. Sugar, water, oxygen, and ATP
d. Sugar, water, sunlight, and oxygen
4. When cells breakdown a sugar molecule completely to produce chemical energy
(ATP), the cells need the following materials_________
a. Sugar and oxygen c. Sugar only
b. Sugar and water d. Sugar and carbon dioxide
5. A vegetable farmer wants to increase his harvest. Which of the following conditions
should the farmer consider?
a. The kind of soil only
b. The amount of water only
c. The location of the plots only
d. All of the above
6. Oxygen is essential in cellular respiration. What is the role of oxygen in the electron
transport chain?
a. It provides a high energy proton. c. It serves as the final acceptor.
b. It releases an electron. d. It forms water.
7. What will happen if ATP and NADPH are already used up at night?
a. Less oxygen will be produced. c. Glucose production will stop.
b. Less carbon dioxide will be used. d. Water molecule will split to form
electrons.
8. Which of the following best explains why planting trees and putting up urban
gardens can help prevent global warming?
a. Plants produce oxygen during day time and perform transpiration.
b. Plants absorb carbon dioxide that contributes to the rising of earth’s
temperature.
c. Plants perform photosynthesis.
d. Plants use up carbon dioxide during photosynthesis, release oxygen to the
environment, and perform transpiration.
9. Sugarcane juice is used in making table sugar which is extracted from the stem of
the plant. Trace the path of sugar molecules found in the stem from where they are
produced.
a. Root ---- stem c. flowers ---- leaf ----stem
b. Leaf ----- stem d. roots --- leaf ---- stem

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10. When cells break down food into chemical energy it undergoes three major
processes, glycolysis, Krebs cycle and electron transport. Which of these processes
provides the most number of ATP molecules?
a. Glycolysis b. Krebs cycle c. electron transport chain d. no idea

UNIT 2
Countless and Active Particles
of Matter

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Unit 2: Countless and Active Particles of Matter

Overview:

In Grade 8 Chemistry, you have learned about the particles of matter. How it
can be used in explaining properties, physical changes, structure of substances and
mixtures. You also learned that particles of matter like atoms are composed of
electrons, protons, and neutrons. An atom has its own structure distinct from the
other kind of atoms. Atoms are present in the elements and these elements are
arranged in the periodic table which can be used as a tool in determining the
properties of elements.

This school year your knowledge about matter will increase as you study this
unit. This unit will provide an opportunity to learn additional atomic models which
you can use in understanding how atoms chemically combine with one another to
form bonds producing compounds. Through this unit, you will also discover that this

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phenomenon is responsible for the numerous organic compounds available for us.
Lastly, you will get to know the mole concept which will give you an idea on how
much particles are equal to one mole and how heavy it is.

Unit 2 is composed of the following modules:

Module 1: Electronic Structure of Matter

Module 2: Chemical Bonding
Module 3: The Carbon Compounds
Module 4: What’s in a Mole?

Each module is packed with interesting activities which will make you enjoy chemistry
class even more.

Are you ready for the continuation of chemistry learning? You may now start with
Module 1.

Unit 2 Suggested Time allotment: 4 hours

MODULE

1 Electronic Structure of Matter

Overview

In Grade 8, you have learned the Rutherford’s atomic model which pictures the atom
as mostly empty space and its mass is concentrated in the nucleus, where you find the
protons and the neutrons. This model has worked well during his time, but it was only
able to explain a few simple properties of atoms. However, It could not explain why
metals or compounds of metals give off characteristic colors when heated in a flame, or
why objects–when heated to much higher temperatures first glow to dull red, then to
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yellow, and then to white. A model different from Rutherford’s atomic model is necessary
to describe the behavior of atoms

Niels Bohr refined Rutherford’s model of an atom. Based on his experiments, Bohr
described the electron to be moving in definite orbits around the nucleus. Much later,
scientists discovered that it is impossible to determine the exact location of electrons in
an atom. In Activity 1, you will learn about the evidence that Bohr used to explain his
model of the atom. In Activity 2, you will do a task that will help you understand that
there is a certain portion of space around the nucleus where the electron is most likely
to be found.

In addition, you will know more about the present model of the atom, which is called
the quantum mechanical model of the atom. It is important for you to understand that
the chemical properties of atoms, ions and molecules are related to how the electrons
are arranged in these particles of matter. You will find out the answers to the following
questions as you perform the activities in this module.

How does the Bohr atomic model differ from Rutherford’s model? What
is the basis for the quantum mechanical model of the atom? How are
electrons arranged in the atom?

The questions above were anchored on the following learning competencies:

 Describe how the Bohr Model of the atom improved Rutherford’s Atomic
Model.
 Explain how the Quantum Mechanical Model of the atom describes the
energies and positions of the electrons.

Excited to discover the answers to the above sited questions? Before you start
studying this module, answer the following pre-assessment.

Pre-Assessment:

1. On the basis of Rutherford’s model of an atom, which subatomic particle is present in

the nucleus of an atom?

a. proton and electron c. proton and neutron

b. neutron and electron d. proton only

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2. If the first and second energy levels of an atom are full, then what would be the total
number of electrons in the atom?

a. 6 b. 8 c. 10 d.18

3. Which atomic model is proposed by Schrodinger?

a. nuclear model
b. planetary model
c. raisin bread model
d. quantum mechanical model

4. Which electron transition results in the emission of energy?

a. 3p to 3s c. 2s to 2p

b. 3p to 4p d. 1s to 2s

5. The symbol “n” in the Bohr theory of atomic structure refers to

a. the energy of electron

b. the total energy of the atom

c. the number of electron in an energy level

d. the orbit in which an electron is found.

6. Which of the following sublevels is correctly designated?

a. 1p5 b. 3f9 c. 2p6 d. 3d11

7. How many orbitals are in the third principal energy level?

a. 3 b. 6 c. 9 d. 12

8. Which configuration is possible in an excited state of electron?

a. 2He : 1s2
b. 1H: 1d1
c. 11Na: 1s2 2s2 2p6 3d1
d. 10Ne: 1s2 2s2 2p5 3s1

9. What are the orbitals present in the fifth principal energy level?

a. s orbital b. s, p orbitals c. s, p, d orbitals d. s, p, d, and f orbitals

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10. For a neutral atom with the electron configuration of 1s 2 2s2 2p5 3s1 , which
statement is false?

a. The atomic number is ten.

b. The 1s and 2s orbitals are filled
c. The atom is in the ground state.
d. The atom is in the excited state

___________________________________________________________________

As early as the 17th century, knowledge about the structure of the atom grew
when scientists began to study the emission and absorption of light from different
elements. In Grades 7 and 8, you have learned about the characteristics and properties
of light. As you perform Activity 1, you will find out what happens when metal salts are
subjected to heat. `The colors you observe could be related to the structure of the atom.

Activity 1: The Flame Test

Objectives:

 determine the characteristic colors that metal salts emit; and

 relate the colors emitted by metal salts to the structure of the atom.

Materials:

0.50 grams of each of the following metal salts:

Calcium chloride 6 pcs watch glass
Sodium chloride 1 pc 10-ml graduated cylinder
Copper(II) sulfate 1 pc dropper
Potassium chloride safety matches
Boric acid
100 mL 95% Ethanol (or ethyl alcohol)
100 mL 3 M hydrochloric acid
Precautions:

1. Wear goggles, gloves and a safety apron while performing the activity.
2. Do this activity in a well-ventilated area.
3. Handle hydrochloric acid with care because it is corrosive.
4. Ethyl alcohol is flammable.
5. Be careful to extinguish all matches after use.

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Procedure:

1. Place each metal salt on a watch glass and add 2 to 3 drops of 3 M

hydrochloric acid.

2. Pour about 3 - 5 mL or enough ethyl alcohol to cover the size of a 1 peso-coin

in the first watch glass. Light with a match and observe the color of the flame.
(This will serve as reference for comparison of the flame color). Wait for the
flame to be extinguished or put out on its own.

3. Repeat procedure No. 2 for each salt. Observe the color of the flame.

4. Write your observation in a table similar to the one below.

Table 1. Color of flame of metal salts

Metal salt tested Element Color of the flame

producing color
Boric acid boron
Calcium chloride calcium
Sodium chloride sodium
Potassium chloride potassium
Copper(II) sulfate copper

Q1. Why do you think are there different colors emitted?

Q2. What particles in the heated compounds are responsible for the production
of the colored light?

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 Q3. How did the scientists explain the relationship between the colors observed
and the structure of the atom?

________________________________________________________________

You have observed that each of the substances you tested showed a specific
color of the flame. Why do certain elements give off light of specific color when heat is
applied? These colors given off by the vapors of elements can be analyzed with an
instrument called spectroscope. See Figure1.

Figure 1. An atomic spectroscope

A glass prism separates the light given off into its component wavelength. The
spectrum produced appears as a series of sharp bright lines with characteristic colors
and wavelength on a dark background instead of being continuous like the rainbow. We
call this series of lines the atomic spectrum of the element. The color, number and
position of lines produced is called the “fingerprint” of an element. These are all
constant for a given element. See Fig. 2.

Figure 2. Atomic spectra of H, Na, and Ne

How did Bohr explain what you observed in Activity 1 and the findings about the
elements in a spectroscope? Individual lines in the atomic spectra of elements indicate
definite energy transformations within the atom. Bohr considered the electrons as

114
particles moving around the nucleus in fixed circular orbits. These orbits are found at
definite distances from the nucleus. The orbits are known as the energy levels, n where
n is a whole number 1, 2, 3…and so forth.

Electrons in each orbit have a definite energy, which increases as the distance of the
orbit from the nucleus increases. As long as the electron stays in its orbit, there is no
absorption or emission of energy. As shown in Figure 3, when an electron of an element
absorbed extra energy (from a flame or electric arc), this electron moves to a higher
energy level. At this point the electron is at its excited state. Once excited, the atom is
unstable. The same electron can return to any of the lower energy levels releasing
energy in the form of light with a particular color and a definite energy or wavelength.
Bohr’s model explained the appearance of the bright line spectrum of the hydrogen
atom but could not explain for atoms that has more than one electron.

Figure 3. Excited state of an electron

Q4. Explain how your observation in Activity 1 relates to Bohr’s model of the atom.
You can explain using an illustration.

Q5. Which illustration below represents the energy of the electron as described by
Bohr? Explain your answer.

a. b

The energy levels of electrons are like the steps of a ladder. The lowest step of the
ladder corresponds to the lowest energy level. A person can climb up and down by
going from step to step. Similarly, the electrons can move from one energy level to
another by absorbing or releasing energy. Energy levels in an atom are not equally
spaced which means that the amount of energy are not the same. The higher energy
levels are closer together. If an electron occupies a higher energy level, it will take less

115
energy for it to move to the next higher energy level. As a result of the Bohr model,
electrons are described as occupying fixed energy levels at a certain distance from the
nucleus of an atom.

However, Bohr’s model of the atom was not sufficient to describe atoms with more
than one electron.

The way around the problem with the Bohr’s model is to know the arrangement of
electrons in atoms in terms of the probability of finding an electron in certain locations
within the atom. In the next activity, you will use an analogy to understand the
probability of finding an electron in an atom.

___________________________________________________________________
Activity 2: Predicting the Probable Location of an Electron

Objective:

 Describe how it is likely to find the electron in an atom by probability.

Materials:

One sheet of short bond paper or half of a short folder

pencil or colored marker with small tip
compass
graphing paper
one-foot ruler
Procedure:

1. Working with your group mates, draw a dot on the center of the sheet of paper
or folder.

2. Draw 5 concentric circles around the dot so that the radius of each circle is 1.0
cm, 3 cm, 5 cm, 7 cm and 9 cm from the dot

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 3. Tape the paper on the floor so that it will not move.

4. Stand on the opposite side of the target from your partner.(Target is the center
which represent the nucleus of an atom). Hold a pencil or marker at chest level
above the center of the circles you have drawn.

5. Take turns dropping the pencil or marker so that it will leave 100 dots on the
circles drawn on paper or folder.

6. Count the number of dots in each circle and record that number on the data
table.

7. Calculate the number of dots per square centimeter (cm 2).

8. Using a graphing paper, plot the average distance from the center on the x-axis
and number of dots per sq.cm on the y-axis.

Data Table:

Circle Average Area of Difference of Number of Number Percent

Numbe Distance Circle, Areas of the Two Dots in of Dots Probability
2
r from Center cm Consecutive Circle per cm2 of Finding
2
cm Circles, cm (E)/(D) dots,
%
(B) (C) (D) (E) (F) (G)
(A)
1 1.0 3.14 25.13 5 0.1920 19.20
2 3.0 28.27 50.27
3 5.0 78.54 75.40
4 7.0 153.94 100.53
5 9.0 254.47 125.66

Q1. What happens to the number of dots per unit area as the distance of the dots
go farther from the center?

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 Q2. Determine the percent probability of finding a dot in each of the circle drawn on
the target by multiplying No. of dots /cm 2 (column D) by the total number of dots
(100). For example: In circle 1(A)

Percent probability = No. of dots /cm2 X 100

= [0.1920 / 100 ] X 100 = 19.20%

Q3. Based on your graph, what is the distance with the highest probability of
finding a dot? Show this in your graph.

Q4. How many dots are found in the area where there is highest probability of
finding dots?

Q5.How are your results similar to the distribution of electrons in an atom?

This activity demonstrates what scientists found out that it is not possible to
know the exact position of the electron. So, Bohr’s idea that electrons are found in
definite orbits around the nucleus was rejected. Three physicists led the development of
a better model of the atom. These were Louie de Broglie, Erwin Schrodinger, and
Werner Karl Heisenberg. De Broglie proposed that the electron (which is thought of as a
particle) could also be thought of as a wave. Schrodinger used this idea to develop a
mathematical equation to describe the hydrogen atom. Heisenberg discovered that for a
very small particle like the electron, its location cannot be exactly known and how it is
moving. This is called the uncertainty principle.

Instead, these scientists believed that there is only a probability that the electron
can be found in a certain volume in space around the nucleus. This volume or region of
space around the nucleus where the electron is most likely to be found is called an
atomic orbital. Thus, we could only guess the most probable location of the electron at
a certain time to be within a certain volume of space surrounding the nucleus.

The quantum mechanical model of the atom comes from the mathematical solution
to the Schrodinger equation.

The quantum mechanical model views an electron as a cloud of negative charge

having a certain geometrical shape. This model shows how likely an electron could be
found in various locations around the nucleus. However, the model does not give any
information about how the electron moves from one position to another.

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 Figure 4. Average distance of electrons having high and low energies

Figure 4 shows that the darker an area, the greater is the probability of finding the
electron in that area. The quantum mechanical model also gives information about the
energy of the electron. The model also describes the region of space around the
nucleus as consisting of shells. These shells are also called principal or main energy
levels. The principal energy levels or shells may have one or more sublevels. These
sublevels are assigned with letters: s, p, d, f, and g as shown in Table 2.

Table 2. Principal Energy Levels and Sublevels of Electrons

Principal Number of Type of Sublevel and number of Maximum

energy level, Sublevels orbitals number of
n electrons
1 1 1s (1 orbital) 2
2 2 2s (1 orbital), 2p (3 orbitals) 8
3 3 3s (1 orbital), 3p (3 orbitals) 18
3d (5 orbitals)
4 4 4s (1 orbital), 4p (3 orbitals) 32
4d (5 orbitals), 4f (7 orbitals)
5 5 5s (1 orbital), 5p (3 orbitals) 50
5d (5 orbitals), 5f (7 orbitals)
5g (9 orbitals)

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 As shown in Table 2, the principal quantum number always equals the number of
sublevels within that principal energy level. The maximum number of electrons that can
occupy a principal energy level is given by the formula 2n 2, where n is the principal
quantum number.
Q6.Based on Table 2, how many types of orbitals are in principal energy level three
(3)?

Q7.How many atomic orbitals are in the highest sublevel of principal energy level
three (3)?
__________________________________________________________________

Figure 5. Shapes of s Orbital and p Orbital

Orbitals have specific energy values. They have particular shapes and direction
in space. The s orbitals are spherical, and p orbitals are dumbbell-shaped, as shown in
Figure 5. Because of the spherical shape of an s orbital, the probability of finding an
electron at a given distance from the nucleus in an s orbital does not depend on
direction, unlike the three kinds of p orbitals which are oriented along the x, y, and z
axes. So they different orientations in space, p x, py, and pz.

The shapes of other orbitals (d and f orbitals) were derived from complex calculation
and will not be discussed in this module.

In an atom, electrons and the nucleus interact to make the most stable
arrangement possible. The way in which electrons are distributed in the different orbitals
around the nucleus of an atom is called the electron configuration.

Table 3. Arrangement of electrons in the atoms of the first 10 elements

O R B I T A L
Chemical 1s 2s 2px 2py 2pz Electron
Symbol Configuration

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 1H ↑ 1s1
2He ↑↓ 1s2
3Li ↑↓ ↑ 1s22s1
4Be ↑↓ ↑↓ 1s22s2
5B ↑↓ ↑↓ ↑ 1s22s22px1
6C ↑↓ ↑↓ ↑ ↑ 1s22s22px12py1
7N ↑↓ ↑↓ ↑ ↑ ↑ 1s22s22px12py12pz1
8O ↑↓ ↑↓ ↑↓ ↑ ↑ 1s22s22px22py12pz1
9F ↑↓ ↑↓ ↑↓ ↑↓ ↑ 1s22s22px22py22pz1
10Ne ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ 1s22s22px22py22pz2

1H = element hydrogen with an atomic number of 1.

Atomic number is the number of proton = the number of electron for an atom

Use this table as guide for the next activity.

Activity 3: Electron Configurations

Objectives:

 Write the electron configuration of the elements in the third period;

 Determine the pattern of filling the orbitals based on the given distribution for the
first 10 elements; and

 Devise rules in filling up the orbitals.

Materials:

Pen and paper

Periodic table

Procedure:

1. Work with your group mates to write the electron configurations for the elements
in the third period of the periodic table.

2. Compare the electron configurations of the second period (see Table 3) and the
third period elements.

Q1. Do you see patterns in the distribution of their electrons?

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 Q2. What are these patterns you have observed?

Q3. What do you think are some rules that apply in filling up
the orbitals for the elements from atomic number 1 to 18?

Based on Activity 3, you were able to write the electron configuration of an element
using the periodic table as a guide. Recall from Grade 8 that the elements are arranged
in the periodic table in the order of increasing atomic number. This also means that the
elements are arranged according to the number of electrons.

If you noticed from Table 3, both hydrogen and lithium have one electron in the
highest energy level. Beryllium has two, and boron has three. So, the number of
electrons in the highest energy level of the elements is the basis of their location on the
periodic table. Since the experimental basis of the periodic table is chemical properties
of the elements, knowing the arrangement of electrons in an element will help us
understand and predict their chemical properties.

Summary:

 Rutherford’s nuclear atomic model describes the atom as mostly empty space.
Its mass is concentrated in the nucleus that consist of protons and neutrons.
However it could not explain the chemical properties of elements.

 Bohr’s atomic model describes the atom like a solar system, where the electron
is found only in specific circular paths, or orbits, around the nucleus.

 In the Bohr model, each electron carries a fixed amount of energy and does not
lose energy as long as it stays in its given orbit. The fixed energies that the
electrons have are called energy levels. An electron that has received enough
energy can jump to a higher energy level. When the electron returns to a lower
energy level, energy is emitted in the form of light.

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  The Bohr model was later replaced by a model of the atom that showed that
electrons are not limited to fixed orbits around the nucleus.

 Through mathematical calculations, scientists explained that there is only a

probability that the electron can be found in a certain volume in space around the
nucleus. This volume or region of space around the nucleus where the electron is
most likely to be found is called an atomic orbital

 Schrodinger formulated a mathematical equation that describes the behavior of

the electron. The solution to the equation is used to calculate the probability of
finding the electron at a particular region in space around the nucleus.

 The quantum mechanical model of the atom describes the atom as having a
nucleus at the center around which the electrons move. This model describes a
region in space where the electron is most likely to be found.

 An electron is imagined to be a cloud of negative charge having a certain

geometrical shape. The electrons are arranged in principal or main energy levels
that consist of one or more sublevels.

 The way in which electrons are distributed in the different orbitals around the
nucleus of an atom is called the electron configuration. Filling of electrons start
from lower energy level to highest energy level

Summative Assessment:

I. Multiple Choice: Select the best/correct answer.

1. Who proposed the probability that electrons will be found in certain locations
around the nucleus of an atom?

A. Neils Bohr C. Ernest Rutherford

B. Erwin Schrodinger D. J.J. Thomson

2. Which of the following statements is NOT true of the atomic model of Bohr?

A. The hydrogen is made up of a positively charged nucleus

B. The electron revolves around the nucleus in a circular orbit.

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 C. The energy of the electron in a given orbit is not fixed.
D. An electron can absorb or emit a quantity of radiation.

3. Which orbital designation has the highest energy?

A. 2s B. 2p C. 3d D. 4s

4. Which statement is incorrect?

A. Orbital is a region in an atom where an electron can be found.

B. An electron can absorb energy when it jumps to a higher energy level.
C. An electron can emit energy when it jumps to a higher energy level.
D. Filling of electrons in an atom starts from a low energy level to the highest
energy level.

5. What occurs when an electron moves from high energy level to a low one?

A. another electron goes from a low energy level to a high one

B. the atom moves faster
C. colored light is given off
D. this process is not possible

6. Which combination describes the flame color of the compound when heated?

A. sodium chloride – orange C. potassium chloride – blue

B. copper(II) sulfate – violet D. boric acid – red
II. Shown here are orbital configurations for the elements named. Each configuration
is incorrect in some way. Identify the error in each and write the correct
configuration.

1. carbon : 1s2 2s2 2px2

2. calcium: 1s22s22px22py22pz23s23px23py23pz23d113d21
3. chlorine: 1s22s22px22py22pz23s23px23py24s1

4. aluminum: 1s22s22px22py22pz23s23d11
5. titanium: 1s22s22px22py22pz23s23px23py23pz2 3d12 3d22

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 Suggested Time allotment: 14-16 hours
Unit 2
MODULE

2 Chemical Bonding

Overview

It is interesting to look back at the lessons you have learned about matter when
you were in Grades 7 and 8. Do you still remember them? Yes! In g
Grade 7, you were able to describe the properties of metals and non-metals and to
recognize elements and compounds. In Grade 8, you observed different common
changes such as evaporation, condensation, boiling, and melting that helped you learn
about the particles that matter is made of. You have also learned that the elements are
systematically arranged and grouped in the Periodic Table of Elements. Your knowledge

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about matter is continuously growing. In fact, in the previous unit you were introduced to
how electrons in different atoms are distributed. You have learned a lot so far!

Studying this module will certainly increase your understanding about matter.

Get your periodic table. What do you notice about the electronic configuration of
the noble gases? You’re right! Except for helium, all of them have eight electrons at the
outermost energy level. The sharing or the complete transfer of electrons causes an
atom to have the same electronic configuration as that of the nearest noble or inert gas.
The sharing or the complete transfer indicates that the atom has attained stability. Either
the sharing or the complete transfer of electrons leads to the formation of compounds.

Going through this module will make you understand what is happening in the
atoms during the formation of compounds. Look at the periodic table. Did you notice
the vertical arrangement of the elements? This is called family or group. Notice the
number in each group? Do you know what information it gives you? It tells about the
number of valence electrons. Do you still remember the meaning of valence electrons?
Valence electrons give you the number of electrons at the outermost energy level of the
atom. This is the information you need to know in order for you to determine whether
atoms transfer, accept, or share electrons to become stable. Why do we need to talk
about the transfer or the sharing of electrons? You will discover the answer to this
question as you study this module.

Further, you will find out the answer to the following questions:

How are ionic and covalent compounds formed?

Why is an ionic compound different from a covalent compound?

How is a metallic bond formed?

The following objectives will help you focus as you go about studying this module.

Learning Competencies/Objectives
 Explain the formation of ionic and covalent bonds.
 Recognize different types of compounds (ionic or covalent) based on their
properties such as melting point, hardness, polarity and electrical and thermal
conductivity.
 Explain properties of metals in terms of their structure.
 Explain how ions are formed.

Before you study this module, please answer the pre-assessment below.

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Pre-Assessment:

Direction: Encircle the letter of the best answer for each question.

1. Which of the properties of atoms is the most suitable reference for the kind of bond
that will take place between/among them?
a. atomic size b. electronegativity
c. ionization energy d. electron affinity

2. What kind of particle is produced after covalent bonding?

a. atom b. molecule
c. ion d. electron

3. How does ionic bonding take place?

a. Two non-metallic elements of different kinds form strong forces of attraction.
b. Two non-metallic element of the same kind form strong forces of attraction.
c. A non-metallic element like fluorine is attracted to a metallic element like sodium.
d. A metallic element like sodium transfers an electron to a non-metallic element
like fluorine.

4. What kind of chemical bond will form between two oxygen atoms?
a. ionic bond b. metallic bond
c. polar covalent bond d. nonpolar covalent bond

5. Which of the following type of bonds will have the highest electrical and thermal
conductivity?
a. ionic bond b. metallic bond
c. polar covalent bond d. nonpolar covalent bond

6. Why can metals be hammered without breaking?

a. They are ductile.
b. They are not brittle.
c. They are malleable.
d. Its particles are strong.

7. When does covalent bonding take place?

a. It takes place when atoms share electrons with one another.
b. It takes place when the attraction between atoms is strong.
c. It takes place when atoms collide with one another.
d. It takes place when atoms attain stability.

8. Nitrogen (N) belongs to family 5A and it is diatomic. How many nonpolar covalent
bonds will there be in N2 molecule?

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 a. 1 b. 2 c. 3 d. 4

9. Which of the following will have the highest melting temperature?

a. sodium chloride (salt) b. paraffin wax (candle wax)
c. sucrose (table sugar) d. lead wire

10. Which among the following shows that an atom is stable?

a. having 2 valence electrons b. having 4 valence electrons
c. having 6 valence electrons d. having 8 valence electrons

After doing this pre-assessment, you are now ready to do the succeeding
activities of this module.

There are concepts you need to know in order to fully understand why atoms
form compounds. Let us start with the basic information, the number of valence
electrons, octet rule, and electronegativity.

Activity 1: Mapping the Periodic Table

Objectives:
 Identify the number of valence electrons of atoms.
 Compare the electronegativity and ionization energy values of metals and non-
metals.

Materials:
Periodic Table
Crayons

Procedure:
1. Locate the metals, non-metals, and noble gases in figure 1. Color the area with
metallic elements blue; the non-metallic elements yellow; and the noble gases
green.

Q1. Where can you find metals, non-metals, and noble gases in the periodic
table of elements?
Q2. Which number will give you an idea on the number of valence electrons?
Q3. What do you notice in the number of valence electrons of metals, non-
metals, and noble gases?

1 18

H He
2 13 14 2 13 14 15 16 17

Li Be B C N O F Ne
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 Na Mg Al Si P S Cl Ar

K Ca Ga Ge As Se Br Kr

Sn
Rb Sr In Sb Te I Xe

Pb
Cs Ba Tl Bi Po At Rn

Figure 1. Periodic Table of the Representative Family/Group

2. Observe the number that corresponds to the valence electrons, electronegativity

and ionization energy of metals and non-metals using a periodic table.
Q4. What kind of element has:
a. less than 4 valence electrons?
b. more than 4 valence electrons?
c. low electronegativity?
d. high electronegativity?
e. low ionization energy?
f. high ionization energy?
The valence electrons are the electrons directly involved in forming bonds to form
compounds. It is important that you know the number of valence electrons so that can
illustrate how bonds are formed. It is good that you have found out that metals have low
electronegativity and non-metals have high electronegativity because this property plays
an important role in forming compounds. Do you know what electronegativity means?
Electronegativity is a measure of the tendency of an atom to attract electrons, the
higher its value, the higher its tendency to attract electrons. How about ionization
energy? Did you know that ionization energy is the energy needed to pull or remove
one or more electron/s from a neutral atom? The lower the ionization energy the easier
it is to remove its valence electrons.

You can also show the number of valence electrons through the Lewis Symbol.
This symbol is composed of the chemical symbol of the element and dots that represent
the number of valence electrons.

The next activity will make you familiar with the Lewis Symbol.

Activity 2: Lewis Symbol

Objectives:
 Write the Lewis Symbol of the common metals and non-metals.

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  Show the relationship among the number of valence electrons, electronegativity,
and ionization energy.

Materials:
Periodic Table of Elements
Procedure:
Use the given periodic table of elements to determine the number of valence electrons.
You may refer to the group number where it belongs in filling up the table below.

Table 1. Lewis Symbols of Some Elements

Electronegativity Ionization
Element Family or Lewis Value Energy
Group Symbol (kJ/mol)
lithium 1 Li . 0.98 520
fluorine
sulfur
calcium
nitrogen
aluminum

Q1. Arrange these elements in increasing:

a. valence electrons
b. electronegativity values.
c. Ionization energy.
Q2. What do you notice with the number of valence electrons, electronegativity values
and ionization energies of the elements?
Q3. What kind of element has the greatest tendency to attract electrons? Why?
Q4. What kind of element requires high energy to remove its valence electrons? Why?

Examine the periodic table below. Does it verify your answers in Q1 and Q2?

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 Source: http://curriculum.nismed.upd.edu.ph

Ionization Energy of the Main-Group Elements in kJ/mol

1 18

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 H He
1311 2372
2 13 14 2 13 14 15 16 17

Li Be B C N O F Ne
520 1312 800 1085 1402 1314 1681 2080

Na Mg Al Si P S Cl Ar
496 738 578 786 1012 1000 1251 1520

K Ca Ga Ge As Se Br Kr
419 1312 579 761 947 941 1140 1351

Rb Sr In Sn Sb Te I Xe
403 1312 558 709 834 869 1008 1170

Cs Ba Tl Pb Bi Po At Rn
376 1312 589 716 703 813 926 1037

You have just learned the relationship among the number of valence electrons,
electronegativity and ionization energy. You also realized that it is easy to write the
Lewis Symbol of the representative element. The information that you found out from
the previous activity will be helpful in understanding chemical bonding.

Do you know why atoms form compounds? Have you heard about the Octet
Rule? Atoms always strive to attain the most stable arrangement of electrons. Atoms
are stable if their electrons have the same kind of arrangement as that of noble gases,
where the s and p orbitals are filled with electrons except for helium, where only the s
orbitals are filled up. All the noble gases except for helium have 8 valence electrons.
The Octet Rule tells you that elements gain or lose or share electrons to achieve the
electronic configuration of the nearest noble gas. Thus after chemical bonding,
elements become isoelectronic with the nearest noble gas in the periodic table.

Metals have low electronegativity and ionization energy, thus they tend to
transfer or loose electrons. Non-metals have high electronegativity and ionization
energy. They have a greater tendency to attract electrons towards themselves. Thus
non-metals tend to gain electrons.

You will gain information about chemical bonding that involves gaining and losing
electrons as you do the next activity.
Activity 3: Bonding by Transfer of Electrons

Objectives:
 Illustrate how an ionic bond is formed.
 Show how ions are formed.

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Materials:
Periodic Table of Elements

Procedure:
1. Select a metallic and a non-metallic element. Write the Lewis Symbol of the
selected elements. Take note of the electronegativity value of both elements.
Subtract the electronegativity value of the metallic element from the non-metallic
element.
..
.
Na EN = 0.90 :Cl: EN = 3.0
.
Thus:
2.1 – 0.90 = 2.1

*If the difference is greater than 1.9, complete transfer of electron/s is

possible.

2. With the use of an arrow, show the complete transfer of electrons.

..
.
Na :Cl:
.
3. Indicate the formation of cation and anion.
Na+Cl-

After ionic bonding, sodium (Na) became isoelectronic with neon (Ne) while chlorine
became isoelectronic with argon (Ar), thus both sodium and chlorine attained stability.
Isoelectronic means sodium (Na) attain the same electronic configuration with neon
(Ne) and in the case of chlorine it acquired the same configuration with that of argon
(Ar). Thus, both of them become stable.

4. Make 5 combinations that will result to ionic bonding by following steps 1-3.

Q1. What kind of element forms cation after ionic bonding?

Q2. What kind of element forms anion after ionic bonding?
Q3. Why do ions form after ionic bonding?
Q4. Did the atoms attain stability after ionic bonding? Explain you answer.
Q5. How can you tell that ionic bonding will take place between metals and non-
metals?
Q6. Will all combinations of metals and non-metals form ionic bond? Why?

Try aluminum and chlorine. Will they form an ionic bond?

. ..
Al: EN = 1.5 :Cl: EN = 3.0
∙

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 Based on the difference in the EN values of Al and Cl, the difference is only 1.5,
these two elements cannot form an ionic bond. In this case, there is not enough energy
to facilitate the complete transfer of electrons. Instead, another bond is formed, the
covalent bond, in which sharing of electrons takes place. This sharing helps the Al and
Cl atoms attain stability.

There are two types of covalent bond: the polar covalent bond and the
nonpolar covalent bond. If the electronegativity difference is equal to 0.4 or less, it
results to a nonpolar covalent bond. If the electronegativity difference is less than 1.9
and more than 0.4, polar covalent bond is formed.

Try to do the next activity to find out if covalent bonding takes place. Take note of
the Octet Rule in considering the number of bonds that will be formed between atoms.
These steps will help you figure out if sharing of electrons will take place.

a. Get the total available valence electrons in a compound.

For CO2
carbon atom has 4 valence electrons
oxygen atom has 6 valence electrons

Total Available Valence Electrons (TAVE) = (1 C atom x 4) + (2 O atoms x 6)

= 4 + 12
= 16

b. Compute for the Octet Rule requirement that each atom should have 8
valence electrons to become stable.
Number of Electrons based on Octet Rule = (1 C atom x 8) + (2 O atoms x 8)
= 8 + 16
= 24

c. Subtract a from b, then divide the difference by 2 because a pair of shared

electron is equal to 1 bond. The quotient will give you the number of bonds
around the central atom.

(24 – 16)
Number of bonds =
2
= 4

Thus, there will be 4 bonds surrounding a carbon atom as shown in the Lewis
structure:
.. .. .. ..
:O::C::O: or :O=C=O:

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 Can you do the same for the next activity? Let’s see!

Activity 4: Bonding by Sharing of Electrons

Objectives:
 Explain how covalent bonding takes place.
 Illustrate the sharing of electrons.

Materials:
Periodic Table of Elements

Procedure:

1. Show how the sharing of electrons form covalent bond in the following
compounds:
a. ammonia (NH3)
b. water (H2O)
c. hydrogen chloride (HCl)
d. nitrogen gas (N2)
e. oxygen gas (O2)
f. methane (CH4)
g. hydrogen gas (H2)
h. phosphine (PH3)
i. sulfur dioxide (SO2)
j. chlorine gas (Cl2)

Supply Table 2 with the data obtained in number 1.

Table 2. Types of Covalent Bonds

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 Chemical Type of Bond
Compound Formula Lewis Structure (polar covalent/nonpolar
covalent)

ammonia

water

hydrogen
chloride

nitrogen gas

oxygen gas

methane

hydrogen gas

phosphine

sulfur dioxide

chlorine gas

Q1. How do covalent bonds form between atoms?

Q2. What kind of element usually forms covalent bond? Is it possible for metals and
non-metals to form nonpolar covalent bond? Why? How about polar covalent bond?

Why?
Q3. Why is it that diatomic molecules always form nonpolar covalent bonds?
Q4. Differentiate polar covalent bond from nonpolar covalent bond.

What have you learned about covalent bonds? Is it now clear to you that covalent
bonds result from the sharing of electrons? Unlike ionic bonds, there is no complete
transfer of electrons in covalent bonds, just sharing of electrons.

In covalent bonding, a pair of shared electrons is equal to one (1) bond. Notice
that after the sharing of electrons, each of the atoms in the compound attains a stable
configuration and a covalent compound is formed. Such compound could exist as
independent units called molecules. As a whole, the molecule does not carry a charge.

Recall that an ionic bond is formed when a metal bonds with a non-metal while a
covalent bond exists between or among non-metals. However, there are cases when
polar covalent bond involves a metal and a non-metal, like in the case of aluminium
chloride (AlCl3).

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 Is it possible that metals form bonds with one another? Can you visualize how it
will be? The next activity will ask you to make a representation of how you think metallic
bonding takes place.

Activity 5: Bonding Among Metals

Objectives:
 Make a model of a metallic bond.
 Relate the properties of metals to the kind of bond they are made of.

Materials:
drawing pen

Procedure:
1. Recall from Activity 3 how metals behave to attain stability.
2. Visualize what will happen to a group of metallic atoms.
3. Prepare a model that will represent a metallic bond. You may draw it.
Q1. What do you think will make bonding among metals possible?

Your teacher will explain to you how metallic bonding takes place. After she
explains, try to describe some metallic properties. Try to explain those properties in
terms of the way metallic atoms are bonded together.

In Table 3, list down the metallic properties that you know and try to explain why
metals possess those properties.

Table 3. Metallic Properties

Metallic Explanation
Property
Metals are lustrous because when light strikes the surface of the
Luster metal the loosely-bound electrons near the surface move and
reflect the light giving the metal a shiny appearance.

Based on the properties you have listed above, make a list of the uses of metals.
Table 4: Uses of Metals

Metal Uses
1. copper Electrical wiring, metal sculpture, and component of jewelry

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 2.
3.
4.
5.
6.

Deeper understanding of the properties of metals can be explained through the

way its atoms are bonded together. It is amazing to realize that as your knowledge in
matter is continuously growing you acquire better understanding of the things around
you and the phenomena happening to them.

So far, you have learned about the three types of chemical bonding. Perform the
next activity to find out if you have fully understood the three types of chemical bonding.

Complete the table below.

Table 5: Types of Chemical Bonds

Material Type of Chemical Bonds

BH3 (borane)
CaF2 (calcium fluoride)
KCl (potassium chloride)
Al (aluminium foil)
Cu (copper wire)
I2(iodine gas)
CO (carbon monoxide)

It’s good that you were able to recall the different types of chemical bonding.
Knowledge about the type of bond helps you relate the basic properties of the
compound. Like what you have done with metallic bonding, ionic and covalent
compounds also have properties which show the type of chemical bond the compound
has. Do you want to find out these properties on your own? Go and perform the next
activity!

ctivity 6: Differences between Ionic and Covalent Compounds

Objectives:
 Recognize ionic and covalent compound based on their physical properties.

Materials:
improvised electrical conductivity apparatus

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 distilled water
alcohol burner
metal spoon
sugar (sucrose)
grated paraffin wax (candle wax)
salt (sodium chloride)
vetsin (monosodium glutamate)
vials or very small bottles
medicine dropper

Procedure:
1. Get a pinch of salt, place it in a spoon, and heat it with the use of an alcohol
burner in 1 minute. Do the same with vetsin, sugar, and grated candle wax.
Record what you observe in column 1 of Table 6.
2. Place a pinch of salt, vetsin, sugar, and grated candle wax on a clean dry sheet
of paper. Label each sample. Let the electrodes of the electrical conductivity
apparatus touch each of the solid sample. Be sure you clean the electrodes
before transferring to the sample. Record your observations in column 2a of
Table 6.
3. Transfer each sample to individual vial. Add approximately 3 mL of distilled water
in each vial and label. Observe the solubility of each sample in the distilled water.
Record your observations in column 3 of Table 6. Test the conductivity of the
compound with distilled water. Record your observations in column 2b of Table 6.
Fill out the table below.

Table 6: Properties of Some Compounds

Electrical Conductivity
(x-did not conduct
electricity Type of
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 Reaction to -conduct electricity) Solubility Compound
Heat (2) in Water (ionic/polar
(melted (a) (b) (soluble/ covalent/
Compoun easily/ insoluble) nonpolar
d did not melt Sample Sample covalent)
easily) without with (3) (4)
(1) water
water

salt
vetsin
wax
sugar

Q1. What type of compound:

a. dissolves easily in water?
b. conducts electricity in solution?
c. melts easily?
Q2. Explain why salt and vetsin can conduct electricity in solution?
Q3. Make a general statement about the properties of ionic and covalent compounds.
Q4.What common properties did you observe in this activity?

You have noticed that ionic compounds conduct electricity when in solution but
not in solid phase and they are generally soluble in water. Covalent compounds are
non-conductors of electricity in solid phase and in solution. Unlike ionic compounds,
they melt easily, so they have low melting temperature.

Summary:

Let us have a synthesis of the concepts you have learned in this module:

 The valence electrons are the outermost electrons which are directly involved in
chemical bonding.
 Lewis symbol is composed of the symbol of the element and dots which
represent the number of valence electrons of an atom that can easily be
determined through the family/group number in the Periodic Table of Elements.
 Atoms form bonds with one another to become stable and attain the electronic
configuration of the noble gas nearest it.
 An ionic bond involves complete transfer of electrons, thus ions are formed. It
involves metals with low electronegativity and non-metals with high
electronegativity.
 Ionic compounds conduct electricity when in solution but not in solid phase.
 Ionic compounds are generally soluble in water and in polar solvents.
 A covalent bond involves the sharing of electrons that results in the formation of
covalent compound whose representative particle is a molecule. As a whole, a
molecule does not carry a charge.

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  Covalent bonds may be polar or nonpolar.
 Two identical non-metallic atoms always form nonpolar covalent compound such
as N2, O2, H2, F2 and other diatomic molecules.
 Non-identical atoms with electronegativity difference higher than 0.4 and lower
than 1.9 produce polar covalent bond.
 Covalent compounds are non-conductors of electricity in the solid phase and in
solution. They have a lower melting temperature than compounds formed by
ionic bonds.
 Metallic bonding exists in metals through the attraction between the freely-
moving valence electrons and the positively charged metal atom. The valence
electrons of these metal atoms are usually called “sea of electrons.”
 Thermal and electrical conductivity in metals are due to the free flow of electrons
in the solid phase. Aside from these properties, metals are lustrous, malleable,
and ductile. These properties are related to the kind of bonding metals have.

Summative Assessment

Write the letter of the best answer.

1. Element X belongs to Group 1. Which of the following best describes element

X?

a. high electronegativity
b. high ionization energy
c. low electronegativity
d. a non-metallic element

2. What will most likely happen to a non-metallic atom after ionic bonding?
I. It forms a cation
II. It forms an anion
III. It becomes stable
IV. It becomes unstable

a. I & II b. II & III c. III & IV d. I & IV

3. What kind of bond will result when two identical non-metallic atoms combine?
a. ionic bond c. polar covalent bond
b. metallic bond d. nonpolar covalent bond

4. Choose 2 elements that would likely form an ionic bond among the following
elements: Li, Si, F, Ne
a. Li and Si b. Si and F c. Ne and Si d. Li and F

5. How is the bond in Br2 different from the bond in MgF2?

a. The bond in Br2 is metallic while the bond in MgF2 is covalent.

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 b. The bond in Br2 is ionic while the bond in MgF2 is covalent.
c. The bond in Br2 is covalent while the bond in MgF2 is ionic.
d. There is no bond difference between the two.

6. Why do atoms react with one another to form chemical bonds?

a. to attain stability b. to form compounds
c. to form molecules d. to produce ions

7. What kind of force is present in ionic bond?

a. repulsive force b. electrostatic force
c. neutral force d. retentive force

8. Which of the following substances when dissolve in water will conduct electricity?
a. glucose b. oil
c. gasoline d. muriatic acid
9. What bond holds the atoms of the elements in Groups 1and 2 of the Periodic
Table?
a. nonpolar covalent bond b. polar covalent bond
c. metallic bond d. ionic bond

10. Which of the following sets of samples has metallic bond, covalent bond and
ionic bonding in this order?
a. bronze, paraffin wax, and salt b. alloy, vetsin, and water
c. gold ring, baking soda, and starch d. coins, salt, and carbon dioxide

Suggested Time allotment: 4 hours

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 Module

3 The Carbon Compounds____

Overview

In the previous module, you have learned about how non-metals make chemical
bonds by sharing electrons from their outer shells to attain stable electronic
configurations. This is also the process by which every carbon compound or organic
compound is formed. In this module, the lessons will be about the uses and properties
of common organic compounds like hydrocarbons, aldehydes and ketones, carboxylic
acids and alcohols.
In this module, you will be able to answer the following key questions:

What are organic compounds?

What are the important uses of organic compounds?

How are the carbon atoms able to form many organic

compounds?

In what ways are the properties of organic compounds

related to their uses?

In your quest to answer the above thought provoking questions you will be able to:
 explain how the structure of carbon atom affects the types of bonds it forms
 recognize the general classes and uses of organic compounds.

Before anything else, please answer the pre-assessment prepared for you.

Pre-Assessment:
Write the letter of the correct answer.

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1. Which of the following statements best describe organic compounds?

A. Organic compounds are compounds that contain carbon and oxygen only
B. Organic compounds are compounds that are produced by living things
C. Organic compounds are composed mainly of carbon and hydrogen
D. Organic compounds are compounds that contain carbon atoms only

2. How do carbon atoms form many organic compounds?

A. By attracting other elements toward themselves to form the bonds

B. By forming many bonds with other carbon atoms and other elements
C. By sharing their electrons with other metal and non-metal elements
D. By transferring their electrons to the atoms of surrounding elements

3. What is the maximum number of bonds can a carbon atom form?

A. 2 C. 4
B. 3 D. 5

4. Emmanuel Juan, a fisher man, went home with some of his catch and told his
son to cook the fish. But his son said, “father the stove ran out of fuel already”.
Then his father told him to buy some so that they could start cooking the fish.
Which organic compound do you think the boy will buy?

A. kerosene C. lubricating oil

B. gasoline D. isopropyl alcohol

5. Which of the following pairs of organic compounds is highly flammable?

A. gasoline, acetone C. lubricating oil, isopropyl alcohol

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 B. water, ethyl alcohol D. liquefied petroleum gas, kerosene

6. Honey is applying something to the ball bearings of the wheels of her bicycle so
that friction will be minimized. Which of the following material do you think she is
using?

A. vinegar C. kerosene
B. isopropyl alcohol D. lubricating oil

7. A gasoline boy was being scolded by his store manager for smoking in the
vicinity of the gasoline station. Why do you think the manager scolded his
employee?

A. because gasoline is volatile C. because gasoline is viscous

B. because gasoline is flammable D. all of the above

8. Joimee scratched herself when her arm bumped into the concrete post. What do
you think should she apply to make her bruises free from harmful germs?

A. formalin C. water
B. isopropyl alcohol D. acetone

9. Which organic compound is used as a cleaning agent?

A. gasoline C. liquefied petroleum gas (LPG)
B. kerosene D. ethyl alcohol
10. Which hydrocarbon compound has a triple bond in the molecule?

A. octane C. ethene
B. methane D. ethyne

11. How many types of bonds are there in the following hydrocarbon compound?

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 A. 1 C. 3
B. 2 D. 4

12. To which group of hydrocarbon does the molecule with the structure

belong?

A. alkane C. alkene
B. alkyne D. none of the above

13. Ethene is a natural gas produced in plants, which acts as a natural ripening
agent of fruits. Which of the following organic compounds has the same ability to
ripen fruits?

A. butane C. acetylene
B. propene D. pentyne

14. Which alkane will most likely have a very low boiling point?
A. propane C. butane
B. pentane d. hexane
15. What is the common use of methane?

A. disinfectant C. artificial ripening agent

B. fertilizer D. fuel

16. Which are TRUE about the use of isopropyl alcohol?

I. cleaner III. disinfectant

II. fuel IV. fertilizer

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 A. I and II only C. III and IV only
B. II and III only D. I and IV only

17. Salvador has to remove the red paint in the paintbrush so that he could still use it
again next time. What organic compound should he use to remove the paint in
the paintbrush?
A. acetic acid C. kerosene
B. lubricating oil D. formaldehyde

18. Which of the following compounds is a carbonyl compound?

A. C.

B. D. all of the above

19. What organic compound is used by embalmers in treating human cadavers?

A. acetic acid C. methyl alcohol

B. formaldehyde D. acetone

20. Which compound is an alcohol?

A. C.

B. D.

You may now start exploring this module.

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Activity 1: Organic Compounds: Are they Useful?

Organic compounds are group of compounds that contain the element carbon.
Organic compounds contain carbon and hydrogen combined with other elements
namely oxygen, nitrogen, phosphorous, sulfur, and halogens (fluorine, chlorine,
bromine, and iodine) Ethyl alcohol, acetone, gasoline, napthalene, acetic acid, vanillin,
acetylene, and esters are just a few examples of many useful organic compounds.
These kinds of compounds are produced by plants and animals. However, these
carbon-containing compounds can also be produced artificially. There are also organic
compounds that are produced from petroleum: liquefied petroleum gas (LPG), gasoline,
lubricating oil and kerosene. These compounds have different uses in the community.
Many organic compounds are formed because of the special characteristics of
the element carbon. A carbon atom has four (4) valence electrons. This kind of atomic
structure makes the carbon atom able to form four covalent bonds with atoms of other
elements and other carbon atoms. Carbon atoms can also make many types of
arrangements: single bond, double bond, and triple bond. With these abilities of the
carbon atoms, chemical bonds between carbon atoms and other elements can form
different kinds of compounds with short and long straight and branched chained
structures such as the following compounds.

Methane Isopropyl Alcohol Acetylene

Objective:
In this activity, you will be able to recognize the uses of common organic
compounds.

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Materials:
paper and pen pentel pen manila paper

Labels or Pictures of the following products:

gasoline acetone kerosene acetic acid LPG ethanol
Procedure:
1) With your groupmates, use the labels/pictures of the materials to answer the
following questions:

Complete the table about the uses of the compounds. Using a check mark, indicate
the uses of the compounds. You may have more than one check mark per sample
depending on its use/s.

Table 1: Organic compounds and their uses

Organic Compounds
Gasoline Ethanol Acetone LPG kerosene Acetic
acid
Beverage
Food
Antiseptic
Uses Fuel
Cleaner
(* This activity is adapted, with minor modification, from Glencoe Physical Science Texas Edition .(1997).
Glencoe/McGraw-Hill Companies Inc., page 369)

Q1. What do you think are the characteristics of the materials which give their
uses?
Q2. Why do you think these kinds of organic compounds are very important?

You just learned the important uses of common organic compounds that are
commonly used. In the next activity, you will learn about the properties of these common
compounds that will help you to appreciate their specific uses.
______________________________________________________________________
Activity No. 2: Properties of Common Organic Compounds

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 Every kind of organic compound has specific properties or characteristics.
Although these compounds may show similarities in some properties, these compounds
do not have exactly the same properties.
Gasoline, kerosene, diesel oil, lubricating oil, vanillin, acetic acid, and ethyl
alcohol are organic compounds with different properties. Gasoline, for example, has a
strong odor, is volatile, and highly flammable. In this activity, you will find out about the
properties-namely, odor, viscosity, volatility, and flammability-of some other common
organic compounds.
Odor is the smell of the compound. Every compound has its own specific odor.
Viscosity is a measure of a liquid’s resistance to flow. Volatility is the measure of the
tendency of a compound to evaporate or turn into gaseous state. Flammability is the
measure of how easily material burns.

Objectives:
 Observe the properties of common organic compounds; and
 Relate these properties to their uses.

Materials
kerosene stop watch 4 pieces of half inch-plastic beads
lubricating oil paper and pen 4 pieces of ¼ sheet of long bond papers
ethyl alcohol calculator 25 mL graduated cylinder
diesel oil matches 4 identical test tubes ( about 5 inches)
4 medicine droppers 4 bottle crowns (tansan)

Warning:
Follow the procedure carefully, you are about to use
flammable substances.

Prepare sand or wet rags to be used in case of fire.

Procedure

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 1) a. With your group, use the table below to record your data from this activity.
Table 1. Properties of Common Organic Compounds

Viscosity Volatility Flammabilit

(average (the time it y (average
Materials Odor Phase time it takes the time it takes
takes the liquid to the material
marble to evaporate) to burn
reach the completely)
bottom)

Kerosene
Lubricating oil
Diesel oil
Ethyl alcohol

b. Place 15 ml of each liquid in the four (4) identical test tubes and label each
test tube according to the liquid it contains.
c. Observe the materials and write the phase and odor of the materials on the
table.
2) Testing the viscosity of the materials
a. Fill a test tube with the first liquid, drop one plastic bead, and then cover it
tightly with a cork or rubber stopper.
b. Invert the test tube so that the bead falls and touches the cork as shown in the
illustration.
c. Quickly turn the test tube in an upright position. Determine the time it takes the
bead to fall or reach the bottom of the test tube.
d. Procedures a, b, and c should look like the illustration below.

Drop the bead and Invert the test tube Quickly turn the test
cover the test tube tube in upright position

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 3) Testing the Volatility of the Materials

a. Using a medicine dropper, put two drops of each liquid material on the
separate pieces of bond papers. You and your group mates should do
this at the same time and place it on the armrest.

b. Record the time it takes the papers to get dry. This is equivalent to the time it
takes the liquid to completely evaporate.

3) Testing for Flammability of the Materials

Warning:
Wear mask before performing the following procedure.
Have the sand or wet rags near you while doing the test
for flammability.

a. Prepare four bottle crowns (tansan) and then place a cotton bud in each
crown.
b. Wet the cotton buds with10 drops of the liquid materials.
c. Ignite each wet cotton bud using a lighted match stick.
d. Record the time it takes each cotton bud to burn completely.
e. Repeat steps a, b, c and d four (4) more times so that you will have five (5)

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 trials per liquid material.
e. Compute for the average time it takes each cotton bud to burn completely.

*This activity is adapted, with minor modification, from the Teaching Resource Package S & T III-
Chemistry. (1992) of The Philippine-Australian Science and Mathematics Education Project
(PASMEP), University of the Philippines Institute of Science and Mathematics Education
Development, and The Department of Education Culture and Sports (DECS)

Q1. Which material is most viscous? What are the common uses of viscous
materials?

Q2. Which materials are flammable? In what ways are these materials
used?

Q3. Which liquid materials have strong odor and weak odor?

Q4. Why is it important to know the properties of these kinds of organic

compounds?

In this activity, you have learned about the properties of some common organic
compounds and the relationship of these properties to their uses. You were able to
observe in the experiments that kerosene, ethyl alcohol, and diesel oil are flammable
compounds. Ethyl alcohol is a volatile compound and lubricating oil is a thick or viscous
liquid.

In the next activity, you will learn about a specific group of organic compounds,
the hydrocarbons.

Activity 3: The Hydrocarbons

Hydrocarbons are organic compounds that contain carbon and hydrogen atoms
only. Hydrocarbons such as methane, ethane and butane are components of natural
gas. Hydrocarbons are grouped into families namely, alkanes, alkenes and alkynes. The
compounds in each group have certain structures that make their properties different
from the other.
Objectives:

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  Recognize common kinds of alkanes, alkenes, and alkynes and their uses.
 Identify the types of bonds formed in alkanes, alkenes, and alkynes.
 Relate the structures of alkanes, alkenes, and alkynes to their properties.
Materials
bond paper pen
Procedure
1) With your groupmates, use the data in Tables 1 to 3 to answer the questions in
this activity.
Table 1. Alkanes
Boiling
Name Phase Condensed Structural Formula Point
(oC)

Methane Gas CH4 -162

Ethane Gas CH3CH3 - 89

Propane Gas CH3CH2CH3 - 42

Butane Gas CH3CH2CH2CH3 -0.5

Pentane Liquid CH3CH2CH2CH2CH3 36

Hexane Liquid CH3CH2CH2CH2CH2CH3 69

Heptane Liquid CH3CH2CH2CH2CH2CH2CH3 98

Octane Liquid CH3CH2CH2CH2CH2CH2CH2CH3 126

Table 2. Alkenes
Boiling
Name Phase Condensed Structural Formula Point
(oC)

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 Ethene Gas CH2=CH2 -104

Propene Gas CH2=CHCH3 -47

1-Butene Gas CH2=CHCH2CH3 -6

1-Pentene Liquid CH2=CHCH2CH2CH3 30

1-Hexene Liquid CH2=CHCH2CH2CH3 63

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Table 3. Alkynes
Boiling
Name Phase Condensed Structural Formula Point
(oC)

Ethyne Gas C2H2 -84

Propyne Gas
CH C CH3 -47

2-Butyne Gas CH3 C C CH3 8.08

HC C CH2 CH2 CH3

Pentyne Liquid 40.2

Q1. What are the types of bonds present in the following: alkanes, alkenes, and
alkynes?
Q2. Using Tables 1 to 3, what pattern do you observe in terms of the phase, number of
carbon atoms, structure and boiling point of the alkanes, alkenes, and alkynes?
Explain the patterns you observe.
Q3. What do you think will be the boiling point of the next alkane, alkene, and alkyne?
Will the boiling point of each hydrocarbon be higher or lower? Explain your answer.
Q4. Why do you think some hydrocarbons are gases and others are liquids?
Q5. Why do you think there are many hydrocarbon compounds?
Q6. What hydrocarbon compounds are gases and liquids? What are the uses
of gaseous hydrocarbon compounds and liquid hydrocarbon compounds?

You have just learned how the structures of hydrocarbons affect their properties,
such as physical state and boiling point. Your teacher will discuss the uses of these
groups of hydrocarbons. In the next activity, you will learn a common application of
acetylene, an alkyne.

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Activity 4: Which bananas will ripen faster?
Calcium carbide (CaC2) is a compound that is commonly known as kalburo. Fruit
vendors use this substance to speed up ripening of fruits like mangoes and bananas in
just a couple of days. When calcium carbide reacts with water such as moisture in the
air, ethyne gas is produced. Ethyne or commonly known as acetylene is a kind of
alkyne.

Objective:
 Investigate how a common organic compound namely ethyne can ripen fruits
faster than the natural way.
Materials:
Calcium carbide (kalburo) hand gloves
Newspapers face masks
12 unripe, green bananas of same variety small plastic cups
2 empty shoe or fruit juice boxes packaging tape
Warning:
Wear mask before performing the following procedure.
Calcium carbide has a strong and irritating odor.
Make sure that calcium carbide does not come in contact with water!
Procedure:
1) Using a sheet of newspaper, wrap ¼ kilo (250g) of crushed calcium carbide
(kalburo). Make sure that the wrapped calcium carbide will just be enough to fit
the area of the bottom of one shoe box.
2) Put the wrapped calcium carbide at the bottom of the shoe box and cover it with
another piece of newspaper.
3) Place 3 unripe (nearing maturity) bananas of the same kind inside the first box
with calcium carbide. This will be Group A.
4) Do not put wrapped calcium carbide in the other shoe box.
5) Place another set of 3 green, unripe bananas of the same kind in the second
box. This will be Group B.
6) After putting all the bananas in each box A and box B, cover both boxes.

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 7) Leave the shoe boxes for 48 hours.
Q1. What are you going to find out or investigate in the experiment?
Q2. What is the independent variable?
Q3. What is the dependent variable in the experiment?
Q4. Write your hypothesis or prediction about what might happen in the
experiment.
8) After 2 or 3 days, put on your face masks and observe what happened to the
bananas. Write your observation in the data table below.

Observations

Group Number of Ripe Bananas and their

Appearance

A
(with calcium carbide)

B
(without calcium carbide)

Q5. How many bananas ripened in Group A and in Group B?

Q6. Which group has fully ripened bananas?
Q7. What conclusion can you make from the results of your experiment?
Q8. Look for the properties of ethyne and explain how it can introduce ripening of fruits?

In this activity, you were able to observe how ethyne or acetylene, which is an
alkyne, can make banana ripen faster. This is just one of the many applications of
acetylene.
In the next activity, you will learn about the other common organic compounds,
alcohols and carbonyl group containing compounds such as aldehydes and ketones.
______________________________________________________________________

Activity 5: Alcohols and Their Uses

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 Alcohols are another group of organic compounds. These organic compounds
also have very important uses. Some alcohols are used as antiseptic or disinfectant,
some are used as cleaning agents, others are used as components of liquors and a few
alcohols are used as fuel for portable stoves or other types of burners.

Objectives:
 recognize the uses of common alcohols;
 identify similarities in the structures of different kinds of alcohols; and
 relate these similarities to the common properties they have.

Materials:
Labels or pictures of commonly used alcohol products brought by your teacher.
pentel pen paper and pen manila paper

Procedure:
1) With your group, read the labels of the products that contain alcohols.
2) Write in the table below, the names of the products and the alcohol compounds
that are found in the labels of the product and their uses.

Name of Name of Alcohol/s Percent (%) or

Products Present in the amount of Uses
Product alcohol in the
Product

Q1. What are the common products that contain alcohol?

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Q2. Why are these alcohols important?

3) With your group, use the following illustrations of the structures of common alcohols
to answer the following questions.

Ethyl alcohol Isopropyl alcohol Methyl alcohol

Q3. What types of bonds are present in ethyl alcohol, methyl alcohol, and in isopropyl
alcohol?
Q4. What accounts for the similar physical properties of alcohols?

You have learned the uses of common alcohols and the relationship between the
structures of alcohols and their physical properties.

In the next activity, you will learn about simple carbonyl compounds, their
properties and uses.
______________________________________________________________________

Activity 6: What is common between acetone and formalin?

Acetone and formalin are examples of simple carbonyl containing compounds

which have common uses. Carbonyl containing compounds are organic compounds
that contain carbonyl functional group, which is composed of a carbon atom double-
bonded to an oxygen atom: C=O.

Objectives
 Give the common uses of acetone, and formalin.

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  Relate the structures of acetone, and formalin to the carbonyl compounds where
they belong.

Materials:
acetone manila paper
formalin paper and pen
pentel pen
Procedure:

1. With your group, talk about the uses of the simple compounds shown to you by
your teacher.

Q1. What are the common uses of acetone and formalin?

2. With your group, use the illustrations of the structures of acetone, and
formaldehyde (formalin) below to answer the questions.

formaldehyde acetone

Q2. What types of bonds do the common compounds have in their structures?
Q3. Formalin and acetone are common carbonyl containing compounds. Why do you
think they both belong in the group of carbonyl containing compounds?

Summary:

 Carbon atoms have special abilities: carbon atoms can form chemical bonds with
other carbon atoms and other nonmetal atoms in many ways. They can form
single, double, and triple bonds. These abilities of carbon atoms are the reasons
why there are som many kinds of organic compounds.

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  Organic compounds are compounds that are primarily composed of carbon
atoms, which are chemically bonded with hydrogen and other elements such as
oxygen, sulfur, and nitrogen. Organic compounds are naturally produced by living
organisms, but can also be produced artificially.

 Organic compounds such as gasolene, kerosene, ethyl alcohol, isopropyl

alcohol, formaldehyde, acetic acid, acetone, and lubricating oil have important
uses. These uses are based on their specific chemical properties.

 Hydrocarbons are a specific group of organic compounds which contain carbon

and hydrogen only. Alkanes, Alkenes, and Alkynes are the three (3) basic groups
of hydrocarbon compounds. Alkanes are hydrocarbons that have single bonds
between carbon atoms. Alkenes are hydrocarbons that have double bonds
between carbon atoms and Alkynes have triple bonds between carbon atoms.

 Ethyne or commonly known as acetylene is an alkyne hydrocarbon with a

chemical formula C2H2. This organic compound is commonly used as fuel in an
oxy-acetylene welding torch. Ethyne (acetylene) is also produced when Calcium
carbide, CaC2, reacts with water in the air. It has the ability to hasten the ripening
of fruits. That is why fruit vendors use calcium carbide in ripening their fruits in
just a few days.

 Ethene is a gaseous organic compound with a chemical formula CH2CH2. It is a

plant’s compound that is responsible for the ripening of fruits.

 Alcohols are a group of organic compounds that contain a hydroxyl group, -OH,
that is chemically bonded to a carbon atom in the compound. They have special
uses such as a disinfectant, fuel, and as a main component (ethyl alcohol) of
liquor and other alcoholic drinks.

 Carbonyl compounds like acetone, and formaldehyde have a carbonyl functional

group, C=O, which is chemically bonded to a carbon atom in the compound.
These common carbonyl compounds also have important uses: acetone is used
as a cleaning agent like a nail polish remover, and formaldehyde is used in
preserving organic materials like an animal specimen. This is also the compound
used in embalming human cadavers.

Summative Assessment:
Write the letter of the correct answer:

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1. Which are TRUE about organic compounds?

I. organic compounds contain calcium

II. organic compounds contain carbon
III. organic compounds can be produced by living organisms
IV. organic compounds can be produced artificially
A. I, II and III only C. II and III only
B. I and III only D. II, III and IV only

2. Why are carbon atoms able to form many organic compounds?

A. carbon atoms have strong attraction to other elements

B. carbon atoms attract electrons from other atoms
C. carbon atoms can form many types of bonds with other carbon
D. none of the above

3. How many types of bonds can a carbon atom form?

A. 1 C. 2
B. 3 D. 4

4. Marcy’s car stopped at the middle of the road. She found out that her car has
ran out of fuel. Which compound must she buy?

A. kerosene C. lubricating oil

B. gasoline D. water

5. Juan Victor’s grandmother was cooking their supper when she suddenly stopped
and said, “Oh, the tank is already empty!” Then her grandmother asked him to
buy another tank. What did Victor’s grandmother ask him to buy?

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 A. gasoline C. lubricating oil
B. water D. liquefied petroleum gas (LPG)

6. Juan Miguel wants to protect his bicycle’s parts from rusting fast. Which of the
following material do you think will Miguel use?

A. vinegar C. kerosene
B. isopropyl alcohol D. lubricating oil

7. Marcela told her grandson, Miguel, never to play with gasoline. Why do you think
she does not allow him to do it?

A. because gasoline is volatile C. because gasoline is viscous

B. because gasoline is flammable D. all of the above

8. Emmanuel Juan cut his finger accidentally when he was cutting his nails. He has
to apply something on his wound so that it will not get infected. Which
compounds should he use?

A formalin C. kerosene
B. isopropyl alcohol D. acetone

9. Why is it important to know the properties of common liquid materials?

A. To know the uses of the liquids

B. To know possible danger from these kind of material
C. To know how these liquids affect people
D. all of the above

10. Which hydrocarbon compound has a double bond in the molecule?

A. ethane C. propene
B. methane D. propyne

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11. How many types of bonds are there in the following hydrocarbon compound?

A. 1 C. 3
B. 2 D. 4

12. To which group of hydrocarbon does the molecule with the structure

belong?

A. alkane C. alkene
B. alkyne D. none of the above

13. Methane is a component of natural gas. What is the common use of methane?

A. disinfectant C. fuel
B. medicine D. cleaning agent

14. What happens to the boiling point of hydrocarbon compounds when the number
of carbon atoms increases?

A. remains the same C. increases

B. decreases D. increases then decreases

15. What is the common use of ethyne?

A. disinfectant C. artificial ripening agent

B. fertilizer D. antibiotic

16. Which are TRUE about the use of ethyl alcohol?

I. medicine III. disinfectant

II. fuel IV. Fertilizer
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 A. I and II only C. III and IV only
B. II and III only D. I and IV only

17. Veronica wants to change her nail polish because it does not look good with
her new dress. What must she use to remove her fingers’ old nail polish?

A. acetic acid C. acetone

B. lubricating oil D. formaldehyde

18. Which of the following compounds is a carbonyl compound?

A. C.

B. D. all of the above

19. Maria Paula wants to preserve a fish for her project in Biology class. What kind of
compound should she use to preserve the animal?

A. acetic acid C. methyl alcohol

B. formaldehyde D. acetone

20. Which alkene will most likely have the highest boiling point?

A. ethene C. pentene
B. propene D. hexene.

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 Unit 2 Suggested Time allotment: 14-16 hours
MODULE

4 What’s in a Mole?

Overview

In real life situations, pieces of matter are quantified by finding the mass or by
counting. Market vendors for example, would rather sell mongo seeds by getting the
mass and salted eggs by counting. The choice of quantifying goods is determined by
convenience. It is easier to get the mass of rice grains rather than count the grains. It is
more convenient to count the number of eggs rather than get their mass. To measure
these quantities, mass units such as kilogram or gram, or counting units such as dozen

167
or case are being used.
In the laboratory, chemists measure out a chemical substance and react it with
another substance to form the desired quantity of a new product. In this case, chemists
want to know the number of atoms, ions, or molecules because these are the ones that
react with each other. However, these things are too small and too many to count
individually so chemists use a unit called mole to count them by weighing. Like a dozen,
a ream, or a case, a mole also represents a certain number of particles. Can you guess
how many particles are equal to one mole?
As you go through this module you will be able to answer the following key
questions:

How is the mole used to express the mass of a substance?

How is the percentage composition of a given compound determined?

Learning Competencies/Objectives

 use the mole concept to express mass of substances; and

 determine the percentage composition of a compound given its
chemical formula and vice-versa.

Before you work on this module, answer first the pre-assessment prepared for you.
Pre-Assessment:

Direction: Choose the letter of the correct answer.

1. Suppose you were asked to prepare a 250-g chocolate mousse which is 35%
chocolate, 30% cream, 20% milk, 10% sugar, and 5% butter, how much cream are you
going to use?
a. 75 g cream b. 60 g cream
c. 73 g cream d. 62 g cream

2. Cheska measured the mass of 10 pieces of each of the following materials: marble,
pebble, and ballpen cap. What will be her findings based on the data she obtained?
Table 1. Data on Mass
Materials Mass
(10 pieces) (g)
marble 50

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 pebble 35
ballpen cap 20

a. Different materials have different masses.

b. Materials of different kinds differ in amount, color, and texture.
c. The same number of materials has different colors and appearance.
d. The same number of materials of different kinds has different masses.

3. The following are representative particles of matter: which among them represents a
covalent compound?
a. atom b. ion
c. molecule d. particle unit

4. A bag of NPK fertilizer marked 16-4-8 contains 16% nitrogen, 4% phosphorous and
8% potassium, the other 72% is usually inert filler material, such as clay pellets or
granular limestone. What is the mass of nitrogen present in 500g pack of NPK fertilizer?
a. 80g b. 40g
c. 20g d. 10g

5. How many particles are equal to 1 mole?

a. 6.02 x 1022 particles b. 6.02 x 1023 particles
c. 6.02 x 1024 particles d. 6.02 x 1025 particles

6. How can the knowledge about mole be useful for environmentalists?

a. Mole concept can be used in environmental monitoring.
b. It gives information on the most dangerous pollutant in the atmosphere.
c. It gives a feedback on the kinds of pollutants present in the atmosphere.
d. Mole concept can be used in quantifying the amount of pollutant-particles
released in the atmosphere.

7. How can you apply knowledge on percentage composition?

a. In maintaining the quality of food product.
b. In checking the amount of sugar present in the softdrink.
c. In identifying the correct amount of substance present in a sample.
d. all of the above

8. How many percent of hydrogen (H) is present in water (H 2O)?

a. 12% b. 11%
c. 13% d. 10%

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9. Which of the following units is used in expressing the amount of substance in terms
of the number of particles?
a. liter b. gram
c. mole d. Celcius

10. What do you expect to observe in a “Mole Exhibit of Different Substances?

a. different kind of elements
b. different colors of substances
c. showcase of 1mole of different elements having different masses
d. showcase of 1mole of different substances having the same masses

Now that you are done with the pre-assessment, let us perform the activities in this
module to understand the mole concept.

Activity 1: Counting by Getting the Mass of an Object

Objectives:

 Measure the mass of an object.

 Record the mass with the correct number of significant figures.
 Relate the mass of the object to the number of pieces per item.

Materials Needed:
25 pieces paper clips of the same size and kind
Platform balance (preferably with 0.01 precision)

Procedure:

1. Measure and record the mass of 25 pieces paper clip using the platform balance.
Divide the mass obtained by 25 to find the average mass of one paper clip.
Perform three trials.

Table 1: Data on the Average Mass of Paper Clips

Trial Mass (25pieces in g) Average Mass (g) of
one paper clip
1
2
3

2. Get a handful of paper clips and measure their mass. Compute for the number of

170
 paper clips using your data from step #1. Be sure to do it through computation
and not by counting.
3. This time, count the number of paper clips in the handful of paper clips in step
#2.
4. Repeat steps 2 and 3 by getting a different handful of paper clips. Record your
answer on Table 2.

Table 2: Data on the Number of Paper Clips

Number of Paper Clip
Trial Mass of a handful Number of Paper Clips Based on the
of paper clips based on Computation Actual Count
1
2
3

Q1. Is the number of paper clips in step 2 the same as the number of paper clips in step
3? Why do you think so?
Q2. Having an experience in counting by getting the mass, give some ways in which
you can apply this procedure in daily life situations.

You have just experienced how chemists determine the number of particles by getting
the mass. It is impossible to count the number of atoms present in a gold bar or the
number of molecules present in a glass of water but by knowing their masses,
computations can be done which will eventually give the number of particles with the
use of a number called Avogadro’s number.

Avogadro's number is the number of particles in one mole of a substance.

It is a very large number equal to 6.02 x 10 23 particles. So, a mole (mol) of a
substance is 6.02 x 10 23 representative particles of that substance. The representative
particles can be atoms, molecules, or formula units. So, one mole of carbon-12 contains
6.02 x 10 23 atoms, one mole of water contains 6.02 x 10 23 water molecules and one
mole of sodium chloride (table salt) contains 6.02 x 10 23 formula units of sodium
chloride. For you to figure out how large Avogadro’s number is, try to imagine this, “if
you put together 6.02 x 10 23 basketballs, it will be as big as the Earth or if you
have 6.02 x 10 23 rice grains, it would cover the land masses of the Earth to a
depth of 75 meters.” Now that you have realized how big Avogadro’s number is. Let us
try to visualize the number of particles in a given sample.
(*Source: Wilbraham, A.C., Staley, D.D., Matta, M.S. & Waterman, E.L. (2007).
Chemistry, Teacher’s Ed. Boston, Massachusetts: Pearson, Prentice Hall, Inc.)

Example:
How many molecules are there in 4.0 moles of CO 2?

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To answer this question you have to consider this:

1 mole = 6.02 x 10 23 particles

Thus, using dimensional analysis approach, you will be able to convert
number of moles to its equivalent amount in the number of particles.

6.02 x 1023 molecules CO2

4.0 moles CO2 x = 2.41 x 1024 molecules CO2
1 mole CO2
For you to have a feel on how it is being done, you may answer the following questions.

a. How many mongo seeds are equal to 3.50 moles of mongo seeds?
b. How many bananas are equal to 7.50 moles of bananas?
c. How many moles of rice grains are equal to 1.807 x 10 24 grains of rice?
d. How many moles of tomatoes are in 3.01 x 10 23 tomatoes?

Were you able to get the correct answer? Now that you already know how to use
1 mole = 6.02 x 10 23 particles as conversion factor, let us move on to the next activity.
Do substances with the same mass have the same number of particles?
Let’s now have an activity about measuring the mass of an object with the same
number of particles. Do different substances having the same number of particles have
the same masses? You will discover the answers to these questions as you perform
Activity 2.

Activity 2: Total Count Vs. Mass

Objectives:

 Measure the mass of a given number of objects.

 Record the mass showing the precision of the measuring device.
 Convert the number of items to its equivalent mass in grams or vice versa using
the equivalents taken from the result of the activity.

Materials Needed:
5 plastic bottle caps (must be of the same brand)
5 soft drink crowns of the same brand
5 10-centavo coins
platform balance

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Procedure:
1. Measure and record the mass in grams of the above caps, crowns, and coins
in Table 2:
2. From the data you got from step #1, compute for the mass of 1piece and 15
pieces for each kind of material.
3. Measure approximately 25.00g of each material

Table 2. Mass of the Materials

Mass (g) Mass (g) Mass (g) Number of pieces
Materials 5 pieces 1 piece 15 pieces in 25.00 g
plastic bottle cap
soft drink crown

10-centavo coin

Q1. Do the three different materials have the same masses? Explain your
answer.
Q2. Was your expected number of pieces per material the same as the number
of pieces equal to 25.00g?
Q3. What can you infer from this result?

You have observed from this activity that although you have the same number of
items, different objects will have different masses. In the same way, one mole of
different substances always contains 6.02 x 10 23 particles but each of these substances
has a different mass. Examine the sample substances in Table 3. You will observe that
each of the substances contains 6.02 x 10 23 particles.
Table 3. Mass of One Mole of Different Substances
Chemical Molar Mass Number of
Substance Formula (g/mol) Particle
oxygen gas O2 32.00 6.02 x 10 23
Sucrose
C12H22O11 342.34 6.02 x 10 23
(table sugar)
Hydrogen peroxide H2O2 34.02 6.02 x 10 23
Elemental Calcium Ca 40.08 6.02 x 10 23

Are you now convinced that one mole of different substances have different
masses? Remember that one mole of a substance contains 6.02x10 23 particles.
This time, consult the periodic table of elements. Look for the atomic mass of hydrogen,
oxygen, carbon, sulfur, potassium, and phosphorus. What do you observe about their
atomic masses? Each element has its own mass different from the others in the same
way that different compounds have different masses.

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Let us perform Activity 3 to visualize how one mole of different substances differs in
mass.

Activity 3: The Mass of One Mole of a Substance

Objective:
 Compute for the molar mass of common substances.

Materials:
6 pcs 100 mL beaker or small jars of the same size
platform balance
Periodic Table of Elements

Procedure:
1. For table 4-A, consult the periodic table of elements for the atomic mass, which
has the same numerical value with its molar mass. For table 4-B, compute the
molar mass of the compound using this formula:

(Number of atom A x atomic mass of A) + (Number of atom B x atomic mass of B)…

Example: MgCl2 (1 x 24.21g) + (2x 35.45g) = 95.11g

Table 4-A: Molar Mass of Some Common Elements

Element Symbol Mass Molar Mass
(g) (g/mol)
Sulfur (Asupre)
Lead (Tingga)
Copper (Tanso)

Table 4-B: Molar Mass of Some Common Compounds

Compound Chemical Mass Molar Mass
Formula (g) (g/mol)
Water H2O
Table Salt NaCl
Table Sugar C12H22O11
2. Get the mass of an amount equal to one mole of the substances in tables 4-A
and 4-B. Put the sample substances in containers of the same size. Observe
closely the amount equal to one mole.

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Q1. Do you think that one mole of the different substances have the same amount?
Q2. What do you observe about the mass of the substances in Tables 4-A and 4-B?
Q3. Would 1.50 moles of H 2O have the same number of particles as 1.50 moles of any
of the substances you weighed?
Q4. What can you infer about this activity?
Let us have more exercises on the molar mass of the different compounds
common to us.

Table 5. Molar Mass

Chemical Name Chemical Formula Molar Mass (g/mol)
Iron (II) sulphate (ferrous sulfate) FeSO4
Ethyl alcohol C2H5OH
Ammonia NH3
Citric acid C6H8O6
Aluminum hydroxide Al(OH)3

Knowing the number of particles present in one mole of a substance and how to
compute for the molar mass, you are ready for the next activity.

Activity 4: The Relationships among Number of Moles, Mass, and Number of

Particles

Objective:
 Describe the relationships among the number of moles, mass, and
number of particles.
Materials:
sulfur platform balance
sugar watch glass
salt measuring spoon
aluminum foil

Safety Tips
Avoid skin contact with sulfur.

Procedure:

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1. Measure the mass of one tablespoon of each of the following substances:
sulfur; aluminum foil ; sugar; and salt

2. Using the molar mass of each of the substances, in Table 6, compute how many
moles are present in each sample. Record your answer.
3. Compute for the number of particles of each substance.

Table 6. Data on Molar Relationship

Substance Sulfur *Aluminum foil Sugar Salt
Mass (g)
No. of Moles
No. of Particles
*Cut into tiny pieces
Q1. List down the substances based on the following order:
a. Increasing mass (light to heaviest)

b. Increasing number of particles (lowest to highest amount)

c. Increasing number of moles (lowest to highest amount)

Q2. Is the number of particles in the sample directly related to the number of moles?
Why do you say so?
Q3. Is the mass of the sample related to the number of moles? Explain your answer.
Q4. Explain why one tablespoon of different substances does not have the same mass
in grams (g), the same number of moles, and the number of particles.

Now that you have learned the connections and relationships among the mass,
number of moles, and the molar mass of some substances, you can easily figure out its
amount in terms of its mass, the number of moles and the number of particles. Can you
state the relationship between the following properties?
a. Mass and number of moles
b. Number of moles and number of particles

The next activity will help you understand these relationships better.

Activity 5: The Chemist’s Mole

Objective:
 Apply the mole concept in completing a given set of data.
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Material:
Periodic Table of Elements
Procedure

Complete the table with the needed information.

Table 7. Molar Relationships

Substance Molar Mass Representative Mass Number of Number of
(g/mol) Particle (g) Moles Particles
Carbon
Dioxide
44.01 2.5
(CO2)
Gold (Au) atom 1
Glucose
(C6H12O6) 360.36 1.205 x 1024
Calcium
fluoride formula unit
3
(CaF2)
Nitrogen
28.02 140.10
gas (N2)

Q1. When is a particle classified as an atom, a molecule, or a formula unit?

Q2. Show how you will convert the mass of a given sample to number of moles and vice
versa.
Q3. Show how you will compute for the number of particles given the following:
a. Mass of the sample
b. Number of moles of the sample

Test your understanding about the mole concept by answering the following problems at
home.

1. A cancer patient needs to increase his ascorbic acid (C6H8O6) intake to fight cancer
cells. a) How many moles of ascorbic acid does he need to complete the doctor’s
prescription of 13.00g of intravenous ascorbic acid every day for one month? b) How
many molecules of ascorbic acid does he need everyday to fight the cancer cells?

2. Aspartame (C14H18N2O5) is synthetic table sugar substitute in food and drinks. If a

food product needs 0.25 g of C14H18N2O5 to sweeten the Chemitria cupcake, and you
ate this food product, how many molecules of aspartame have you eaten?

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3. During exercise, lactic acid (C3H6O3) forms in the muscles causing muscle cramps. If
5.0 g of lactic acid (C 3H6O3) concentrate in your leg muscles, how many moles of lactic
acid (C3H6O3) are causing you pain?
4. Paraffin (C22H46) is a wax used in candle-making. During combustion, a 20.0 g candle
produces 1.42 moles of CO2. How many molecules of CO 2 are released in the
atmosphere after using the candle?

Applying the mole concept can be a useful quantitative tool in daily life.
Understanding this concept gives you an idea of how many molecules of vitamins and
or medicines are introduced into our body. Given the mass, you also have a clearer idea
of how many molecules of pollutants are produced and released in the environment due
to human activities even though your unaided eyes cannot see them.
In the next activity, you are going to summarize what you have learned from the
previous activities. Recall all the key ideas and make a concept map about them.

Activity 6: Mole Map

Objective:
 Prepare a concept map on the mole concept.

Material:
Activity sheet
Procedure:
Complete the following concept map with the appropriate terms using the
following words: ions, Avogadro’s number, mole, atoms, molecules, particles, mass,
compound, g/mole( molar mass), elements.

MATTER

is made up of

which may be

whose amount may be expressed in terms of

whose mass

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equal to
 is expressed in

Accomplishing the concept map means that you have understood the lessons
you have studied. Let’s proceed to the next topic.

Percentage Composition of a Compound

Are you interested to know how much of an element is present in a compound?

You can answer this question by determining percentage composition.
The mass of each element in a compound compared to the entire mass of the
compound multiplied by 100 percent is called the percentage composition of the
compound. So, the percentage composition of a compound tells you the
percentage of the mass made up by each element in a compound. Let us compare
it in a classroom situation. You are 50 in your section with 21 boys and 29 girls. If you
will be asked what percent of the class are boys and what percent are girls, how are you
going to compute for the answer? If your answer is 42% boys and 58% girls, you got it
correctly! Let us have an example for the compound which is so important to all of us,
water (H2O). The computation below shows the molar mass of water. If you will be
asked to compute for the percentage of oxygen and hydrogen in water, how are you
going to do it?

H2O
1 O atom (16.00 g) = 16.00 g
2 H atoms (1.01g) = 2.02 g
_____________
18.02 g
Did you answer 89% oxygen and 11% hydrogen? Your answer is correct! To get the
percent oxygen, mass of oxygen is divided by the mass of water multiplied by 100%.
The same is true with hydrogen.

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 % Composition of Water

Can you present a general formula for the computation of percentage

composition?

We can have the formula as:

mass of element in the compound

% mass of element = x 100%
mass of the compound

Let us apply this formula to problem solving.

1. Soil that is already depleted of its nutrients needs fertilizer. One of the nutrients
needed to replenish the soil is nitrogen. If you are an agricultural technician helping a
farmer, which among these fertilizers are you going to use? Show your computations to
convince the farmer about your choice.
a. ammonia - NH3
b. ammonium sulfate - (NH4)2SO4
c. ammonium nitrate - NH4NO3

2. Glucose (C6H12O6) is a six-carbon sugar (hexose) which is also known as the blood
sugar. It is an energy source that fuels our body. How many percent of carbon is present
in glucose?

3. The “fuel value” of the hydrogen-containing fuels depends on the mass percentage of
hydrogen (H). Rank the following compounds in terms of their “fuel value” with 1 as the

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highest fuel value and 3 as the one with the lowest value:
a. ethane (C2H6)
b. propane (C3H8)
c. ethanol (C2H5OH)

In what other ways can we use percentage composition in our daily lives? Can
you give suggestions for its practical use?

Activity 7: It’s Grocery Time!

Objectives:

 apply the concept of percentage composition in choosing grocery items.

 realize that the amount of substance intake can be monitored with the use
of percentage composition.

Materials:

Grocery item containers or packages (food wrappers, can, bottles etc)

Procedure:

1. Get 3 samples of containers or packages of grocery items such as canned goods,

snacks, and beverages.
2. List the substances written as contents/ingredients on the label. Choose two (2)
substances from each type of grocery item.
3. Research from a chemistry book or from the internet the chemical formula of the
substances on your list.
4. Compute for the percentage composition of the substances you have listed.
Q1. Based on this activity, what food do you regularly consume which gives your body
a lot of carbon (C) atoms and sodium (Na) ions?
Q2. Are these good for your body? Why? Research on how much of these types of
food are recommended for your age group.
Q3. In what other ways can you make use of the concept on percentage composition?

Knowledge about percentage composition is useful in choosing the best fertilizer

that gives higher amount of nitrogen and potassium in the soil. Aside from this, it will
help us to be a wise consumer because it is a good basis of choosing the food product
we need to eat based on its content. Whenever you buy t-shirt, it is good to check
whether it is 100% cotton or just 75% cotton. In terms of product development,
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percentage composition will indicate the correct amount of substances needed in order
to produce the expected product. For example, if a manufacturing company wants to
produce resin, it will not be able to do if it does not know the correct percentage of every
component needed to form resin..

Summary:

It is important that you remember the following ideas from this module:

 Different kinds of materials with the same number of particles have different
masses.
 One mole contains Avogadro’s number of particles equal to 6.02 x 10 23.
 Different substances with the same number of moles have the same number of
particles but they have different masses.
 Molar mass is the mass of one mole of a substance expressed in grams.
 The molar mass of a monatomic element like Na, Li, Mg is numerically equal to
its atomic mass expressed in grams.
 The mass of the substance divided by its molar mass gives the number of moles
of the substance.
 The number of moles multiplied by Avogadro’s number gives the number of
particles.

 Percentage composition of a compound tells you the percentage of the mass

made up by each element in a compound

Summative Assessment

Direction: Choose the letter of the correct answer.

1. The label of the dark chocolate indicates that its mass is 150g and it is 70% cacao, if
you consume the whole chocolate bar, how much cacao did you eat?
a. 105 g cacao b. 45 g cacao
c. 100 g cacao d. 50 g cacao

2. What is the representative particle of ionic compounds?

a. atom b. ion
c. molecule d. formula unit

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3. How many particles are there in one mole of any kind of substance?
a. 3.01 x 1023 b. 6.02 x 1023
c. 3.01 x 1024 d. 6.02 x 1024

4. Moth balls (paradichlorobenzene-C 6H4Cl2) are used as cockroach repellent. It is often

placed inside the cabinet. If 1 piece of moth ball weighs 5.0g and your mother put 3
pieces in your cabinet, how many molecules of paradichlorobenzene-C 6H4Cl2 (Molar
Mass = 147.00 g/mol) will be circulating inside your cabinet considering all the moth
balls have sublimed?
a. 6.02 x 10 22 molecules of C6H4Cl2
b. 6.02 x 10 23 molecules of C6H4Cl2
c. 6.14 x 10 22 molecules of C6H4Cl2
d. 6.14 x 10 23 molecules of C6H4Cl2

5. Who among the following students describes the result of the activity on counting by
weighing correctly?
Ann – Different sets of materials having the same mass have different number
of pieces.
Dan – Different sets of materials have the same number of pieces and the
same mass.
Tom - The same sets of materials, have the same number of pieces but
different masses.
a. Ann b. Dan
c. Tom d. none of them

6. The roots of the plants absorb the nutrients from the soil. For the farmers, it is
important to strengthen the root system of their plants to ensure its growth. Potassium is
the mineral responsible for a healthy root system. If you were a farmer, which of the
following fertilizers are you going to use?
a. K2SO4 b. K2O
c. KCl d. K2CO3

7. Methane (CH4Molar Mass = 16.04 g/mol) is one of the greenhouse gases. If 32.08 g
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of CH4 is released in the atmosphere, how many molecules of CH 4 are added in the
atmosphere?
a. 1.20 x 1024 b. 1.20 x 1023
c. 6.02 x 1024 d. 6.02 x 1023

8. The presence of SO2 in the atmosphere causes acid rain. How many percent of
sulfur is present in SO2 (Molar Mass = 64.07g/mole)?
a. 40.00% b. 49.95%
c. 60.00% d. 50.05%
9. Arrange the following substances from the lightest to the heaviest:
Cl2; CH4; H2O; NH3; N2

a. H2O< NH3< N2< CH4< Cl2 b. CH4< NH3< H2O< N2< Cl2
c. N2< Cl2< H2O< CH4<NH3 d. NH3< CH4< Cl2< H2O< N2

10. Why is mole concept important?

a. It is useful when converting between grams and atoms or molecules.
b. It gives us a convenient way to express large numbers
c. It can be applied to any type of particle representative
d. All of the above

11. Ammonium nitrate (NH4NO3 Molar Mass = 80.06g/mole) is a substance used to

produce dinitrogen monoxide (N2O), a dental anesthetic. Determine the mass percent of
N in ammonium nitrate?
a. 35.00% b. 40.65%
c. 39.50% d. 43.68%

12. People usually use hydrogen peroxide (H 2O2 Molar Mass = 34.02 g/mole) to clean
their wounds. If Cheska used 1.0 g of H 2O2 to clean her wound, how many mole of H 2O2
did she use?
a. 0.035 mole b. 0.030 mole
c. 0.029 mole d. 0.025 mole

13. In cold areas, many fish and insects, including the common housefly produce large
amounts of glycerol (C3H8O3 Molar Mass = 92.11 g/mole) to lower the freezing point of
their blood. How many percent of oxygen is present in glycerol?
a. 52.11% b. 50.11%
c. 51.11% d. 53.11%

14. Ethyl butanoate (C3H7COOC2H5) is the substance responsible for the aroma of
pineapple. What is the molar mass of ethyl butanoate?

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 a. 118.00 g/mole b. 117.12 g/mole
c. 120.12 g/mole d. 116.18 g/mole

15. Calcium carbonate (CaCO3 Molar Mass = 100.09 g/mole) is an antacid used to
neutralize extra acid in the stomach. Lorie is prescribed by the doctor to take 250mg-
tablet of CaCO3 three times a day. How many moles of CaCO 3 will Lorie consume for 3
days?
a. 0.0252 moles b. 0.0225 moles
c. 0.0242 moles d. 0.0235 moles

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