Chemistry

PARTICLE THEORY OF MATTER

What is matter?

- Matter is the physical material of the universe. It is anything that occupies space and has mass
and can be perceived by our senses.
- Everything is made of tiny particles. They are always in a constant movement. The more energy
they gain the fast they move.

Solid – Closely packed in a fixed pattern. Vibrating but cannot move past each other. Particles are held in
position by a very strong force called bonding.

Liquid – Packed closely and cannot be squashed. Forces between particles are weaker than in solids but
stronger than in gas. They are not arranged in a fixed pattern, they can move around freely.

Gas – Are very far apart and move randomly at a high speed. There is no force holding them together.
They can be compressed.

Solid-liquid= liquify

Liquid-gas= Vaporizing

Solid-gas= Subliming

Solid Liquid Gas

Shape Retains a fixed shape Fills the shape of a Fills the shape of a
container container
Volume A fixed volume. Cannot A fixed volume. Can be Changing volume. Can
be compressed compressed be compressed
Arrangement of A fixed pattern Not arranged in a fixed No pattern or shape
particles pattern
Distance between Closely packed Packed closely but can Very far apart
particles be squashed
Attraction between A very strong force Forces between liquid There is no force
particles called bonding particles are weaker holding them together
than in solids but
stronger than in gas
Motion of particles Vibrating but cannot They can move around They move randomly at
move past each other freely a high speed
CHEMICAL AND PHYSICAL CHANGE
• An extensive property is a property that depends on the amount of mass in a sample such as
mass or volume.

• An intensive property is a property that depends on the type of matter in a sample, not the
amount of matter, such as hardness.

Properties of matter

There are two broad classifications of the properties of matter:

• A chemical property is the ability of a substance to undergo a specific chemical change, that can
only be observed or measured by changing a substance's chemical identity, e.g. flammability or
enthalpy of combustion.

• A physical property is a quality or condition of a substance that can be observed or measured

without changing the substance’s composition.

A Matter of Change

Matter can change form via physical and/or chemical changes.

 A physical change involves a change in the form of matter but not in its chemical identity, eg. a
change of state.

- Easily reversible*
- No new product formed
- Often a change in state

 A chemical change (chemical reaction) involves a change in which one or more kinds of matter
are transformed in a new kind of matter or several new kinds of matter, e.g. decomposition of
water to produce hydrogen and oxygen gas.

- Not easily reversed*

- New products are formed
- Reactants are used up
- Often heat, light, sound or
effervescence occurs
- Electricity may be produced
- A precipitate may form

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 - Q1. Describe the difference(s) between intensive and extensive properties of matter and give an
example of each.

Extensive depends on the mass whilst intensive depends on the type of matter in the sample.

- Q2. Explain why all samples of a given substance have the same intensive properties.

- Q3. Name three states of matter.

Solid, liquid and gas

- Q4. In what ways are liquids and gases alike? In what way are liquids and solids different?

Liquid and gases both can be compressed and take up the shape of the container they are in.
However, a solid cannot be compressed and retains a fixed shape.

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 ELEMENTS, COMPOUNDS AND MIXTURES
Pure Substance

A pure substance contains only one kind of particle. A pure substance has distinct chemical properties.

There are two types of pure substances:

- Elements

Elements are composed of a single type of atom. Therefore, all the atoms of one element are the same
as each other BUT different from the atoms of all the other elements. -- --- Compounds

Elements are pure substances that cannot be

Pure substances formed from two or more elements in decomposed into other components by normal
which the elements are always combined in the same chemical means.
fixed (i.e. constant) proportions by mass are called
All the known elements are arranged by atomic
compounds.
number (the number of protons they have) into
Compounds can be decomposed into other periods and groups in the Periodic Table of the
components by chemical means. Elements.

MIXTURES
Most forms of matter are not chemically pure, that is, they are not pure substances. Matter that is not
chemically pure is referred to as a mixture. In some mixtures, the individual components can retain all of
their physical properties.

There are two types of mixtures:

• Homogenous mixtures

A homogenous mixture is a mixture where the components that make up the mixture are uniformly
distributed throughout. So, no matter where you take the sample from it will be the same. This means
that a sub sample of a homogeneous mixture is representative of the whole.

Some common forms of homogeneous mixtures include solutions. Solutions can be solids and gases as
well as liquids.

• Heterogeneous mixtures

Heterogeneous mixtures consist of two or more regions, called phases, that have different properties.
The matter in question is not uniform throughout and a sub-sample is not representative of the whole.

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CLASSIFYING MATTER – HETEROGENEOUS AND HOMOGENEOUS

Q1. Explain the term phase as it relates to homogeneous and heterogeneous mixtures.

- The term phase refers to the regions of space of which different states of matter and
combinations occur.

Q2. How are a substance and solution similar? How are they different?

- A substance is matter that is uniform in composition. A substance can be an element or

compound. A solution is another name for a homogeneous mixture. It is also uniform in
composition, but a solution is made by physically combining two or more substances.

Q3. How is a compound different from an element?

- The difference between an element and a compound is that an element is made up of the same
type of atom throughout while a compound is composed of multiple different elements. Both
are pure chemical substances found in nature.

Q4. How can you distinguish a pure substance from a mixture?

- A pure substance contains only one type of particle whilst a mixture has multiple different types
combined together. Separated using physical means.

Q5. Classify each of these samples of matter as an element, a compound, or a mixture: table sugar, tap
water, cough syrup, nitrogen.

- Table Sugar-Compound, Tap Water-Mixture, Cough Syrup-Mixture, Nitrogen- Element

Q6. Name the chemical elements represented by the following symbols: C, Ca, K, Au, Fe, Cu.

- C- Carbon, Ca- Calcium, K- Potassium, Au- Gold, Fe- Iron, Cu- Copper

Q7. How are the items in each of the following pairs similar? How are they different? A) copper and
silver, B) distilled water and saltwater, C) table sugar and table salt.

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Q8. Identify each of the following items as a mixture or compound. Classify the mixture as homogeneous
or heterogeneous: A) raw egg, B) ice, C) gasoline, D) blood.

A) Raw egg- Mixture/Heterogeneous B) Ice- C) Gasoline- Mixture/Heterogenous

SEPARATING MIXTURES

Filtration- The process that separates a solid from the liquid in a heterogeneous mixture is called
filtration. The holes (or pores) in the filter exclude particulates greater than a given size without
restricting the passage of the liquid phase

Evaporation- Evaporation is used for recovering dissolved solid substances from solutions by
evaporating the solvent. The solute “dissolves out” and is left behind.

Distillation- During a distillation, a liquid is boiled to produce a vapour that is then condensed into a
liquid. The solid substances that were dissolved in the liquid remain in the distillation flask because their
boiling points are much higher than the boiling point of the purified liquid.

Magnetic Separation- A mixture of solids where one of the components can be separated using a
magnet to attract particles away from the mixture.

Chromatography- Chromatography is an advanced technique of separation in which individual

components of a mixture are separated from each other using the property of differential migration.
Here, a mobile phase, carrying the mixture, is passed through a selectively adsorbent stationary phase,
which can retain the components of the mixture to different degrees.

Gravity Separation- In gravity separation, a mixture of two immiscible liquids can be separated using
a separating funnel (pictured), the working of which is based on the differences in the densities of the
liquids.

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Q1. What type of properties can be used to separate mixtures?

Some of the types of properties that can be used to separate mixtures are: Filtration. Distillation.
Chromatography. Magnetism. Floatation. Extraction.

Q2. In general, when would you use filtration to separate a mixture? When would you use distillation to
separate a mixture?

The process that separates a solid from the liquid in a heterogeneous mixture. Example is a coffee filter

A liquid is boiled to produce a vapor that is the condensed into a liquid. Example is distilling tap water
from its impurities

Q3. Devise a way to separate sand from a mixture of charcoal, sand, sugar, and water.

Filter the mixture through a wire screen to remove the charcoal, then use a paper filter to remove the
sand from the sugar and water. Being that the sugar will dissolve in water, but the sand will not, the
sugar will pass through the paper with the water, leaving the sand behind. Then use the process if
distillation to separate the sugar from water.

Q4. List three examples of real-world processes for separating mixtures.

- Making pasta. You filter the water from the pasta

- Distillation. Salt from water

Q5. Consider the following properties of the element copper:

a) Copper metal cannot be broken down by a chemical change.
b) Copper reacts with oxygen in air to give copper oxide.
c) Copper, in the form of malachite ore, is found worldwide.
d) Copper and tin compose bronze alloy.

Q6. Classify each of the following copper samples as an element, compound, a homogeneous mixture,
or a heterogeneous mixture:

a) copper wire b) copper oxide

c) malachite ore d) bronze alloy.

Q7. A clear liquid in an open container is allowed to evaporate. After three days, a solid is left in the
container. Was the clear liquid an element, a compound, or a mixture? How did you know?

A mixture; an element would be one pure substance, a compound is chemically combined and so a
mixture (being the clear liquid) was easily separated, leaving the solid residue.

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Q8. The following data refer to the two substances, methyl ethanoate and ethyl ethanoate.

COMPOUND FORMULA MELTING BOILING DENSITY SOLUBILITY

POINT POINT IN WATER
g cm-3
°C °C

methyl C3H6O2 -98 57.5 0.93 miscible

ethanoate

ethyl C4H8O2 -84 77 0.90 miscible

ethanoate

ATOMIC THEORY
Q1. Why did Rutherford’s atomic model need to be replaced?

Rutherford's atomic model could not explain the chemical properties of elements. He stated that the
atom had a solid centre that consisted of positive particles. However, Bohr later proposed that the
nucleus actually had neutral (neutron) within.

Q2. What was the basic new proposal in the Bohr model of the atom?

Bohr proposed that an electron is found only in specific circular paths, or orbits, around the nucleus.
Bohr also established that the nucleus contained neutrally charge particles.

Q3. What does the quantum mechanical model determine about electrons in an atom?

The quantum mechanical model determines the allowed energies an electron can have and how likely it
is to find the electron in various locations around the nucleus. Atomic Structure

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PERIODIC TABLE OF ELEMENTS
How did Mendeleev organise his periodic table?

- He organised them with the terms of their increasing atomic mass.

How is the modern periodic table organised?

Increasing atomic number

Why is it called the periodic table?

- Because of its periodically repeating properties.

What do we call the columns of the periodic table?

- Groups

What do we call the rows of the periodic table?

- Periods

What are they three broad classes of elements?

- Metals, non-metals, metalloids and gases

- Alkali Metals
- Alkaline Earth Metals
- Transition Metals
- Metals metalloid gases non-metals
- Halogens
- Lanthanides and Alcaides
- Noble gases

What is the major contribution of the periodic table?

- It helps us understand the world around us and the atoms that make up everything.

When and how were the noble gases discovered?

- Noble gas is translated from the German noun Edelgas, first used in 1898 by Hugo Erdmann to
indicate their extremely low level of reactivity. The name makes an analogy to the term "noble
metals", which also have low reactivity.

What has been the most recent element to be discovered and proven to exist? Who? How? When?

- Moscovium disovered in 2010 by Y. Oganessian et al. Prepared by alpha decay of tennessine

Groups based on reoccurring physical and chemical properties.

Metals, non-metals and metalloids

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 Metals

Metalloids

Non-metals

 About 80% of the elements in the Periodic Table are metals.

 The metalloids separate the metals and non-metals.
 Most reactive metals in the bottom left of the table (Fr).
 Most reactive non-metals in the upper right (before nobles) of the table (F).

Metals Metalloids Non-Metals

 Conductive – excellent  Like non-metals in most  There is greater variation
conductors of heat and ways in physical properties among
electricity  Have some metallic non-metals than among
 Lustrous – shiny when properties metals.
polished or freshly cut  Can conduct electricity
 Malleable – can be  Specific elements: Boron, Insulators - Either poor
hammered into new shapes silicon, germanium, arsenic, conductors or do not conduct
 Ductile – can be drawn into antimony, tellurium, electricity at all (except
thin wires polonium Carbon)
 High Density – most have
high density (sink in water) Physical State - Low melting
 Physical State – all but and boiling points, usually
mercury are solid at room liquids or gases at room
temperature temperature
 Electronegativity – metal  Not Malleable - Brittle,
atoms have low crumble into powders
electronegativity (give up  Not lustrous - Dull, little
electrons easily to form ions) or no shine

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BONDING
Questions

Q1. Why are alloys more useful than pure metals?

This is because they have superior physical

Q2. Why is it possible to bend metals but not ionic crystals?

Q3. Atoms of which elements tend to gain electrons? Atoms of which elements tend to lose electrons?

Q4. How many electrons will each element gain or lose in forming an ion?

a) calcium (Ca) b) fluorine (F)

c) aluminium (Al) d) oxygen (O)

Q5. Name some alloys that you have used or seen today.

Q6. The properties of all samples of brass are not the same – explain.

Q7. What properties characterise ionic compounds?

Q8. Research why most ionic substances are brittle.

Q9. The melting point of a compound is 1240°C. Is this compound most likely an ionic or a molecular
compound?

Q10. How can you describe the electrical charge of an ionic compound?

Q11. Explain why Neon is monatomic, but chlorine is diatomic.

Q12. Ethyl alcohol and dimethyl ether each have the same molecular formula, C2H6O. Ethyl alcohol has
a much higher boiling point than dimethyl ether. Propose an explanation for this difference.

Q13. True or false: as the electronegativity difference between covalently bonded atoms increases, the
strength of the bond increases.

Q14. Is an alloy a compound? Explain.

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NAMING IONIC COMPOUNDS
Ionic Compound. Between a Metal and Non-Metal. High boiling point. Electrostatic attraction-
oppositely charged ions (Cations and Anion). Conduct electricity when molten or dissolved in a liquid.
Formed by the transfer of electrons. Anions and cations form a lattice structure. Bonds broken by water
and have a net charge of zero. It is hard, brittle and crystalline structures.

Metallic Bond. Between a Metal and Metal. High boiling point. Conducts electricity. Ductile and
malleable. Forms alloys. Surrounded by a mobile sea of electrons and is closely packed by cations.
Crystalline. Attraction of the free-floating valence.

A metal alloy is strong than the original compound, mixture of two or more metals. Better properties
than the original. Metal alloys are homogenous mixtures. Sterling silver, Ag + Cu.

Molecular/Covalent Compound between a Non-Metal and Non-Metal. Water is an example of a

covalent bond. Lower melting and boiling points. Atoms held together by sharing electrons. A molecule
is a neutral group of atoms joined by covalent bonds. Liquid or gas at room temperature. Doesn’t
conduct electricity.

Monatomic Ion: A single atom with a positive or negative charge resulting from the loss or gain of one
or more valence electrons.

- Cations: Metallic elements tend to lose valence electrons to form cations (+ charge).
- Anions: Non-metals tend to gain electrons to form anions (- charge).
- Names of monatomic anions usually end in –ide.

Monatomic Cations

1+ 2+ 3+

Lithium Li+ Beryllium Be2+ Aluminium Al3+

Sodium Na+ Magnesium Mg2+

Potassium K+ Calcium Ca2+

Rubidium Rb+ Strontium Sr2+

Caesium Cs+ Barium Ba2+

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Monatomic Anions

1- 2- 3-

Fluoride F- Oxide O2- Nitride N3-

Chloride Cl- Sulphide S2- Phosphide P3-

Bromide Br- Selenide Se2- Arsenide As3-

Iodide I-

Polyatomic Ions: composed of more than one atom.

1- 2- 3- 1+

Hydroxide OH- Sulfite SO32- Phosphite PO33- Ammonium NH4+

Cyanide CN- Sulfate SO42- Phosphate PO43-

Nitrite NO2- Carbonate CO32-

Nitrate NO3- Chromate CrO42-

Hypochlorite ClO-

Acetate C2H3O2-

Remember: Only the valence electrons are used in bonds

1. Start with 2 separate atoms

2. Metals give electron(s) to the non-metal
3. Atoms become ions
4. Opposite charges stick together

Writing formulae: Ionic Compounds- Has an overall charge of zero

- Li2O – Lithium Oxide

- K3N – Potassium Nitride
- AlCl3 – Aluminium Chloride

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 REMEMBERING
1 What are the major characteristics of the valency electrons in a metal?
Delocalised and formed into a sea of electrons
2 Define 'metallic bonding.'
The bonding between a metal and a metal
3 Explain why metals have delocalised electrons.
When electricity flows, the electrons are considered "free" or “delocalised” only because there
are more electrons than there should be, and because the transition metals, such as iron,
copper, lead, zinc, aluminium, gold etc. are willing to transiently accept and give up electrons
from the d-orbitals of their valence shell.

UNDERSTANDING
4 Explain the following observations in terms of the metallic model.

a You can draw out metals into a wire.

You can do this because metals a ductile and due to the sea of electrons, the atoms can roll
across each other to take up less space. This is because when the array of cations is
sheared.
b You should not stick a metal fork into a power socket.
If the fork enters both the Hot and Neutral slots of the outlet, or the Hot and the Ground slot, the
fork will short that circuit, and the circuit breaker will pop, killing the current. No problem.
If the fork tines enter the Neutral and/or Ground slots, nothing will happen.
If the fork tines enter the hot slot and you are grounded, you will get a shock that will feel like a
very strong "vibration" that comes from 60 hertz frequencies of power.
c You pick up a metal spoon that has been sitting in a cup of hot water and burn your hand.

APPLYING

METALS
5 For each of the following purposes, suggest an important metallic property that makes it
suitable for that purpose.

a) Copper is used in electrical wiring.

- It has a very high thermal and electrical conductivity.
b) Iron is used in construction of bridges.
- It is also strong, ductile and malleable
c) Aluminium is used in saucepans.
- It has a low density and therefore low weight, high strength, superior malleability, easy
machining, excellent corrosion resistance and good thermal and electrical conductivity are
amongst aluminium’s most important properties.

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 d) Jewellery is commonly silver and gold.
- It has an attractive shiny appearance, although it tarnishes easily.
e) Electric light filaments are made of tungsten.
- Highest melting point of any pure metal

COVALENT BONDING
Covalent bonding occurs between a non-metal and a non-metal, through sharing electrons.

Only showing/using valence electrons.

Covalent Compounds: (Lewis dot diagrams)

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