Chem's Studyguide Iq
Chem's Studyguide Iq
Chem's Studyguide Iq
DATE: 15/10/15
GRADE: 9th B
Frequency: is the number of waves that pass a given point per second.
Amplitude: the amplitude of a wave is the waves height from the origin to a crest or from the
origin to a trough.
Electromagnetic spectrum: the electromagnetic spectrum, also called the EM spectrum,
includes all forms of electromagnetic radiation, with the only differences in the types of
radiation being their frequencies and wavelengths.
Quantum: a quantum is the minimum amount of energy that can be lost or gained by an atom.
Plank's constant: Planck proposed that the energy emitted by hot objects was quantized. The
energy of a quantum is given by the product of Plancks constant and the frequency.
Equantum = h. Plancks constant has a value of 6.626 x 10-34 Js, where J is the symbol for joule, the
SI unit of energy. The equation shows that the energy of radiation increases as the radiations
frequency, v, increases.
Photoelectric effect: in the photoelectric effect, electrons, called photoelectrons, are emitted
from a metals surface when light of a certain frequency, or higher than a certain frequency,
shines on the surface.
Photon: a photon is a massless particle that carries a quantum of energy.
Atomic Emission Spectrum (AES): the atomic emission spectrum of an element is the set of
frequencies of the electromagnetic waves emitted by atoms of the element.
EXERCISES (page 166)
Exercise 34 Define the following terms.
a.) Frequency: Frequency is the number of waves that pass a given point per second.
b.) Wavelength: Wavelength is the shortest distance between equivalent points on a
continuous wave.
c.) Quantum: A quantum is the minimum amount of energy that can be lost or gained by an
atom.
d.) Ground state: An atoms ground state is its lowest allowable energy state.
d.) X rays, a.) ultraviolet light, b.) microwaves, c.) radio waves
Exercise 37 What is the photoelectric effect?
A phenomenon in which a metal emits electrons when light of a sufficient frequency shines on
it.
Exercise 45 Radiation Use Figure 5.20 to determine the following types of radiation.
Hz = s-1
Exercise 48 What is the speed of an electromagnetic wave with a frequency of 1.33 x 10 17 Hz and a
wavelength of 2.25 nm?
1 nm = 1 x 10-9 m
Exercise 50 Mercurys atomic emission spectrum is shown in Figure 5.21. Estimate the wavelength
of the orange line. What is its frequency? What is the energy of a photon corresponding to the orange
line emitted by the mercury atom?
Solution:
Exercise 51 What is the energy of an ultraviolet photon that has a wavelength of 1.18 x 10-8 m?
= c/ = (3.00 x 108 m/s) / (1.18 x 10-8 m) = 2.54 x 1016 s-1
Ephoton = h = (6.626 x 10-34 Js) x (2.54 x 1016 s-1) = 1.68 x 10-17 J (Joules)
Exercise 52 A photon has an energy of 2.93 x 10 -25 J. What is its frequency? What type of
electromagnetic radiation is the photon?
Ephoton = h
= Ephoton / h = (2.93 x 10-25 J) / (6.626 x 10-34 Js) = 4.42 x 108 s-1 or Hertz
What type of electromagnetic radiation is the photon? Radio (FM wave or TV)
Nuclear equation: in a nuclear reaction, a new element is created as a result of the alpha decay of
the unstable radium-226 nucleus. It shows the atomic numbers and mass numbers of the
particle involved. The mass number is conserved in nuclear equations.
Beta radiation: the radiation that was deflected toward the positively charged plate. This
radiation consists of fast-moving beta particle.
Beta particle: Each beta particle is an electron with a 1 - charge. Beta particles are represented by
the symbol or e-. The negative charge of the beta particle explains why it is attracted to the
positively charged plate.
Gamma ray: A gamma ray is a high-energy radiation that possesses no mass and is denoted by
the symbol . Because they are neutral, gamma rays are not deflected by electric or magnetic
fields. They usually accompany alpha and beta radiation, and they account for most of the
energy lost during radioactive decay. Because gamma rays are massless, the emission of
gamma rays by themselves cannot result in the formation of a new atom.
EXERCISES (page 129)
Exercise 82 Define alpha particle, beta particle, and gamma ray.
Alpha particle: alpha particle is a helium atom with a 2+ charge.
Beta particle: beta particle is an electron
Gamma ray: gamma rays is high energy radiation
Exercise 85 Radioactive Emissions. What change in mass number occurs when a radioactive atom
emits an alpha particle? A beta particle? A gamma particle?
, mass number decreases by 4;
, no change in mass number; and
, no change in mass number
Exercise 89 Boron-10 emits alpha particles and Cesium-137 emits beta particles. Write balanced
nuclear reactions for each radioactive decay.
10
5
6
3
B
137
Cs
55
Li + 42He
137
Ba +
56
0
-1
Exercise 107 Radiation. Identify the two types of radiation shown in Figure 4.24. Explain your
reasoning.
The deflected beam is alpha radiation because it is deflected toward the negatively charged
plate. The undeflected beam must be neutral gamma radiation.
Lesson 4.3: How Atoms Differ. (pages 115-121)
VOCABULARY
Atomic number: is the number of protons in an atom. The number of protons in an atom
identifies it as an atom of a particular element. The atomic number of an atom equals its number
of protons and its number of electrons.
Isotope: atoms with the same number of protons but different numbers of neutrons.
Mass number: the mass number is the sum of the atomic number (or number of protons) and
neutrons in the nucleus.
Atomic mass unit (amu): is defined as one-twelfth the mass of a carbon-12 atom.
Atomic mass: is the weighted average mass of the isotopes of an element. Because isotopes
have different mass, the weighted average is not a whole number.
EXERCISES (page 129)
Exercise 71 Sulfur. Show that the atomic mass of the element sulfur is 32.065 amu.
Sulfur = S = (31.972amu)(0.9502) x (32.971amu)(0.0075) x (33.968 amu) (0.0421) x (35.967
amu) (0.0002) = 32.065 amu
Zr
40
92
40
52
40
Exercise 73 How many electrons, protons, and neutrons are contained in each atom?
a. 13255 Cs =
b. 5927 Co =
c. 16369 Tm =
d. 7030 Zn =
Symbol
132
55 Cs
59
27 Co
163
69 Tm
70
30 Zn
Electrons
55
27
69
30
Protons
55
27
69
30
Neutrons
77
32
94
40
Exercise 74 How many electrons, protons, and neutrons are contained in each atom?
a. gallium-69=
b. fluorine-23 =
c. titanium-48 =
d. tantalum-181 =
Symbol
Ga-69
F-23
Ti-48
Ta-181
Electrons
31
9
22
73
Protons
31
9
22
73
Neutrons
38
14
26
108
Exercise 75 For each chemical symbol, determine the number of protons and electrons an atom of the
element contains.
a. V =
b. Mn =
c. Ir =
d. S =
Symbol
V
Mn
Ir
S
Electrons
23
25
77
16
Protons
23
25
77
16
Exercise 76 Gallium, which has an atomic mass of 69.723 amu, has two naturally occurring isotopes,
Ga-69 and Ga-71. Which isotope occurs in greater abundance? Explain.
Ga-69 must be more abundant because the atomic mass of gallium is closer to the mass Ga-69
than the mass of Ga-71.
Exercise 77 Atomic Mass of Silver. Silver has two isotopes: 10747Ag, which has a mass of 106.905
amu and a percent abundance of 52.00%, and 10947 Ag, which has a mass of 108.905 amu and an
percent abundance of 48.00%. What is the atomic mass of silver?
Zn-64
30
64
30
34
30
F-19
9
19
9
10
9
Na-23
11
23
11
12
11
Exercise 98 Is the charge of a nucleus positive, negative, or zero? The charge of an atom?
The nucleus is positively charged. The charge of an atom is neutral.
Exercise 102 Boron-10 and boron-11 are the naturally occurring isotopes of elemental boron. If boron
has an atomic mass of 10.81 amu, which isotope occurs in greater abundance?
Boron-11 must occur in greater abundance because the atomic weight of boron-11 is much
closer to the mass of Boron-11 than to the mass of Boron-10.
Exercise 104 Titanium. Use Table 4.9 to calculate the atomic mass of titanium.
f. helium-4
Exercise 7: An element has two naturally occurring isotopes: 14X and 15X. 14X has a mass of 14.00307
amu and a relative abundance of 99.63%. 15X has a mass of 15.00011 amu and a relative abundance
of 0.37%. Identify the unknown element.
Exercise 8: Silver has two naturally occurring isotopes. Ag-107 has an abundance of 51.82% and a
mass of 106.9 amu. Ag-109 has a relative abundance of 48.18% and a mass of 108.9 amu. Calculate
the atomic mass of silver.
A cathode ray tube has a metal electrode at each end and is filled with a gas at low pressure.
One electrode is connected to the negative terminal of a battery (cathode), and the other is
connected to the positive terminal (anode). When current flows, negatively charged particles
called electrons are emitted from the cathode and travel through the tube to the anode.
Question 93 Gold Foil Experiment. How did the actual results of Rutherfords gold foil experiment
differ from the results he expected?
In short, Rutherford expected that the particles to be slightly deflected when they passed
through a gold foil. Instead, he found that some were deflected at very large angles.
Lesson 3.4 Elements and Compounds. (pages 84- 90)
VOCABULARY
Element: an element is a substance that cannot be broken down into simpler substances by
physical or chemical means.
Periodic table: the periodic table organizes the elements into a grid of horizontal rows called
periods and vertical columns called groups or families.
Compound: a compound is made up of two or more different elements that are combined
chemically. Most matter in the universe exists in the form of compounds.
Law of definite proportion: the law of definite proportions states that a compound is always
composed of the same elements in the same proportion by mass, no matter how large or small
the sample.
Percent by mass: the percent by mass is the ratio of the mass of each element to the total mass
of the compound expressed as a percentage.
Law of multiple proportions: the law of multiple proportions states that when different compounds
are formed by a combination of the same elements, different masses of one element combine
with the same relative mass of the other element in a ratio of small whole numbers.
EXERCISES (page 90)
Exercise 28 Complete the table, and then analyze the data to determine if Compounds I and II are the
same compound. If the compounds are different, use the law of multiple proportions to show the
relationship between them.
Analysis Data of
Two Iron
Compounds
Analysis
Data
of Two Iron Compounds
Compound
Total
Mass
Mass FeMass Percent
Mass OFe
Compound
Total
Mass
Mass
(g)
(g)
Mass (g) Fe
O
I
75.00
52.46
22.54
(g)
(g)
(g)
43.53 %Fe=(52.46/75.00)
12.47
I II
75.00 56.00
52.46
22.54
x100=69.95%
Mass
Mass percent OMass
Mass Ratio
Percent Fe Percent
O
(mass Fe/mass O)
%O=(22.54/75.00)
x100=30.05%
69.95/30.05=2.3278
g Fe/1gO
II
56.00
43.53
12.47
%Fe=(43.53/56.00)
x100=77.73%
%O=(12.47/56.00)
x100=22.27%
77.73/22.27=3.4903
g Fe/1g O
Exercise 72
a. What is the percent by mass of carbon in 44 g of carbon dioxide (CO2 )?
100
mass of compound
Percent by mass = (mass of carbon / mass of carbon dioxide) x 100 = (12 g / 44 g) x 100 = 27 %
b. What is the percent by mass of oxygen in 44 g of carbon dioxide (CO2 )?
2 oxygen atoms = 16 g x 2 = 32 g
Percent by mass = (mass of oxygen / mass of carbon dioxide) x 100 = (32 g / 44 g) x 100 = 73 %
or (100% - 27% = 73% ) if we use the result from part (a).
Exercise 74 A 25.3-g sample of an unknown compound contains 0.8 g of oxygen. What is the percent
by mass of oxygen in the compound?
Answer:
Mass of unknown compound= 25.3 g
Mass of oxygen in the sample= 0.8 g
% O= ?
% O= (Mass of oxygen in the sample/ Mass of unknown compound) x 100=
= (0.8 g O / 25.3 g unknown compound) x100 = 3.16%O
Exercise 75 Magnesium combines with oxygen to form magnesium oxide. If 10.57 g of magnesium
reacts completely with 6.96 g of oxygen, what is the percent by mass of oxygen in magnesium oxide?
Mass percentage oxygen = 6.96 g / (10.57 g + 6.96 g) = 39.7%
Lesson 3.3 Mixtures of Matter. (pages 80-83)
VOCABULARY
Mixture: a mixture is a combination of two or more pure substances in which each pure
substance retains its individual chemical properties.
Heterogeneous mixture: is a mixture that does not blend smoothly throughout and in which the
individual substances remain distinct. The salad dressing mixture is an example of a
heterogeneous mixture.
Homogeneous mixture: is a mixture that has constant composition throughout; it always has a
single phase. If you cut two pieces out of a silver mercury amalgam, their compositions will be
the same.
Solution: is a homogeneous mixture that has constant composition throughout; it always has a
single phase.
Filtration: is a technique that uses a porous barrier to separate a solid from a liquid.
Heterogeneous mixtures composed of solids and liquids are easily separated by filtration
Distillation: is a separation technique that is based on differences in the boiling points of the
substances involved. Most homogeneous mixtures can be separated by distillation.
Crystallization: is a separation technique that results in the formation of pure solid particles of a
substance from a solution containing the dissolved substance.
Sublimation: is the process during which a solid changes to vapor without melting, i.e. without
going through the liquid phase.
Sublimation can be used to separate two solids present in a mixture when one of the solids
sublimates but not the other.
Chromatography: is a technique that separates the components of a mixture (called the mobile
phase) based on the ability of each component to travel or be drawn across the surface of
another material (called the stationary phase).
EXERCISES (page 95)
Exercise 58 Describe a method that could be used to separate each mixture.
a. iron filings and sand
It can be used a magnet to draw the iron filings from the sand.
b. sand and salt
It can be added water to the mixture to dissolve the salt. Then, we can filter the mixture to
remove the sand, and then boil off the water so only the salt remains.
c. the components of ink
It should be used Paper chromatography used to separate the components of the ink. If enough
ink is available, distillation may also be used, but is far more complicated than paper
chromatography.
d. helium and oxygen gases
We can cool the gas mixture until it condenses, then distill the condensate.
Exercise 61 Describe how a homogeneous mixture differs from a heterogeneous mixture.
Homogeneous mixtures contain a single phase. Contrary, Heterogeneous mixtures may have
many phases.
Exercise 64 What is chromatography, and how does it work?
Chromatography is a technique used to separate components of a mixture.
Usually, the mobile phase is a gas or a liquid, and the stationary phase is a solid, such as
chromatography paper. The separation occurs because the various components of the mixture
spread through the paper at different rates. Components with the strongest attraction for the
paper travel slower.
Chemical Property
Physical Property
Chemical Property
Physical Property
Physical Property
Exercise 4: Organize. Create a chart that compares physical and chemical properties. Give
two examples for each type of property.
PHYSICAL PROPERTIES
CHEMICAL PROPERTIES
Physical
properties
can
be
observed without changing the
composition of the substance or
sample.
EXAMPLES
Mass
Density
Boiling Point
Melting Point
Conduction of electricity
Shape
Color
Malleability
Ductility
Heat
Exercise 5 Use the data in the table to answer the following questions.
Exercise 6 From a laboratory process designed to separate water into hydrogen and oxygen gas, a
student collected 10.0 g of hydrogen and 79.4 g of oxygen. How much water was originally involved in
the process?
Answer:
Mass of the reactants = mass of the products
Mass of the reactants = mass of water in the process
Mass of the products = mass of hydrogen + mass of oxygen
Mass of water in the process = mass of hydrogen + mass of oxygen
Mass of water in the process = 10.0 g + 79.4 g = 89.4 g
Exercise 7 A student carefully placed 15.6 g of sodium in a reactor supplied with an excess quantity of
chlorine gas. When the reaction was complete, the student obtained 39.7 g of sodium chloride.
Calculate how many grams of chlorine gas reacted.
Answer:
mass of the reactants
=
mass of sodium + mass of chlorine =
mass of sodium = 15.6 g
mass of sodium chloride = 39.7 g
10.0 g
16.6 g
+ mass of oxygen =
Answer:
mass of X = 12.2 g
mass of XY = 78.9 g
mass of X + mass of Y = mass XY
So, substituting and solving for mass of Y:
mass of Y = mass of XY - mass of X = 78.9 g - 12.2 g = 66.7 g
EXERCISES (page 94)
Exercise 43 Classify each as a physical change or a chemical change.
a. breaking a pencil in two
physical
b. water freezing and forming ice
physical
c. frying an egg
chemical
d. burning wood
chemical
a change in color
a change in odor
a change in temperature
the production of a gas or a solid upon mixing.
extensive
c. density intensive
d. length extensive
Exercise 37: Classify each as either a solid, a liquid, or a gas at room temperature.
a. milk
b. air
c. copper
d. helium
e. diamond
f. candle wax
liquid
gas
solid
gas
solid
solid
physical
physical
chemical
physical
chemical
physical