CHEMISTRY ACTIVITY BOOK INTRODUCTION TO CHEMISTRY. MATTER.

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Branches of chemistry

Science

Physical Science

Physics

Chemistry

Life Science

Botany

Zoology

Ecology

Anatomy

Earth science

Geography

Geology

chem

istr

y

Organic chemistry

Inorganic chemistry

Physical chemistry

Analytical chemistry

Biochemistry

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GLOSSARY - CONTENT SPECIFIC VOCABULARY – BRANCHES OF

CHEMISTRY

Read the definition and provide a suitable terms and translation for them from

the box

Chemistry organic chemistry inorganic chemistry

biochemistry analytical chemistry physical chemistry

matter science

TERM

(TRANSLATION)

DEFINITION

anything that has mass and occupies space

the study of the composition of matter and the

changes it undergoes

the study of living things

the study of chemicals containing carbon

the study of chemicals that do not, in general, contain

carbon

a body knowledge obtained through a set of methods

and techniques

the study of the mechanism, the rate, and the energy

transfer that occurs when matter undergoes a change

the study of the composition of substances

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Activity 1.2 Match the project with the proper chemistry discipline.

a. measuring mercury in seawater 1. biochemistry

b. studying enzymes in cells 2. organic chemistry

c. measuring the electrical properties

of solutions 3. inorganic chemistry

d. synthesizing new carbon

compounds 4. physical chemistry

e. making new compounds for

energy processes 5. analytical chemistry

Activity 1.3 In this activity you have to state your opinion.

Stating your Opinion

In my opinion, …

My personal view is that …

I might be wrong but …

Personally, I think …

That is why I think …

I am sure/certain/convinced that …

I have read that …

List three careers that require some knowledge of chemistry. State why you

think they need knowledge of chemistry.

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1. MATTER

GLOSSARY - CONTENT SPECIFIC VOCABULARY - MATTER

Read the definition and provide a suitable terms and translation for them from

the box

luster hardness flexibility color density

mass volume elasticity texture solubility

light transmission conductivity brittleness

TERM

(TRANSLATION)

DEFINITION

The ability to dissolve in water or any solvent.

The ability to allow light to pass through.

How an object feels

How much space a substance takes up

The color a substance looks like

How much stuff there is in a substance (how heavy

an object is)

How tightly packed the molecules in a substance are

The ability to bend without breaking.

The ability to reflect light. Shiny.

Resistance to being scratched by another material

Easily breaks into pieces. Fragile.

The ability to let heat and electricity pass through it.

The ability to be stretched without breaking, to go

back to original size and shape.

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Activity 2.1 Properties of matter

Identify the property of matter as described. Choose from the list:

1. Chlorine gas is yellow- green. ………………………………

2. Iron will always sink in water. ………………………………….

3. A paper clip can be bent. ………………………………………..

4. A rock is 29 kilograms…………………..

5. No mineral can scratch a diamond except another diamond. ………….

6. When polished, metals are very shiny like mirrors. ………………….

7. One kilogram of cotton takes up more space than one kilogram of sugar.

…………………………..

8. Salt easily dissolves in water. ………………………….

9. Copper is a good material to make electrical wires and cooking pots.

…………………………………….

10. The glass bottle is transparent. …………………………….

11. Plastic is very smooth to touch …………………………………

12. An egg breaks into pieces when thrown on the ground. ………………

13. A rubber band can be stretched and it returns to its original shape.

…………………………………..

COLOR TEXTURE BRITTLENESS MASS

ELASTICITY HARDNESS VOLUME CONDUCTIVITY

LUSTER DENSITY LIGHT TRANSMISSION

FLEXIBILITY SOLUBILITY

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PHYSICAL AND CHEMICAL PROPERTIES OF MATTER

Activity 2.2 What are the differences between physical properties and

chemical properties of matter?

Give examples of each.

Physical Properties Chemical Properties

Examples:

Examples:

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Activity 2.3 Define each physical property of matter and fill in the

blanks for each example given.

Name of the

Property Definition

Examples

1. State of Matter

There are three states of

matter. Water in a lake is

found in the …………..state,

water in your ice cube tray is

found in the ……………..

state, and water in steam is

found in the ………… state.

2. Taste

Sugar tastes …………… but

lemons taste ………...

Nothing in a chemistry lab

should ever be …………….

Even if one of the ingredients

is a common food item, once

it is used for a lab, it is

considered potentially

…………….

3. Odor

Old dirty gym socks smell

…………………. and roses

smell …………. Never

………….anything in a

chemistry lab unless

instructed to do so. If

smelling a substance, the

………………. method

should be used to sniff it.

4. Color

A fire truck is ………….. but

the sky on a sunny day is

……………. The leaves on

the trees in the summer are

…………, but the color of the

sun is ……………. . The

color of an orange is

………….!

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5. Luster

A piece of paper is …………

because it does not reflect

much light, but the chrome on

a car is …………… because

it reflects a lot of light.

Another dull thing is

……………. and another

shiny thing is …………...

6. Clarity

A piece of glass is ………… ,

meaning that it lets all light

pass through it, maple syrup is

…………..because it lets

some light through it, and

mud is …………….. because

it lets no light pass through it.

7. Texture

The surface of a bowl feels

………… but the surface of

the cement sidewalk feels

………….. The fur of a cat

feels ………….. The surface

of an eraser feels …………. .

8. Hardness

On Mohs’s hardness scale of

minerals, a ………… is the

hardest thing known on Earth

with a hardness level of

…………. An emerald is also

hard but it has a hardness

level of ……………...

9. Solubility

Water and vinegar mix

together completely and

therefore, vinegar is

………….. in water. Salt is

also ……….. in water because

it will dissolve completely in

water. Neither oil nor sand

will dissolve in water, and that

is why they are considered

……….. in water.

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Name of the

Property Definition Examples

10. Viscosity

Water is ………..viscous

than oil, and that is why it

pours out of its container

more easily than oil does.

Ketchup is ……….

viscous than oil, and that

is why it’s ……….. for it

to pour out of its

container.

11. Malleability

…………….. is very

malleable and that is why

we use it to make foil to

wrap our food. Other

substances like glass are

……... malleable, because

it would break instead of

change shape. Wood is

…......................... while

copper is …………...

12. Ductility

Many metals like

…………… and ……….

can easily be drawn into a

thin wire. Substances like

water and cement are not

…………….. .

13. Density

Rubber is ………… dense

than water and that is why

it will float in water. A

penny is……….. dense

than water and that is why

it will sink to the bottom

of the water. Water in its

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………….. state is less

dense than water in its

……… state. That is why

ice floats on water.

14. Electrical Conductivity

……………….. is a

………. electrical

conductor, and that is why

it is used as the main

material for the wiring

found in most homes and

electronics. Plastic is

………. a good conductor

of electricity and that is

why it is used to

………… electrical wires.

15. Melting Point

The melting point of

water is ……. °C and the

boiling point of water is

…… °C. The melting

point of ……….. is

1063°C and the ………..

point of gold is 2856°C

16. Boiling Point

17. Crystal Form

If you look with a high

powered microscope, you

can observe that sugar

crystals are oblong and

slanted at the sides, but

the crystal form of salt is

shaped more like a

…………...

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Name of the

Property Definition Examples

18. Magnetism

Substances like steel are

……………. to magnets so

they are considered

………………. Substances

like glass are …………….

attracted to magnets and

are called ……………….. .

CHEMICAL PROPERTIES OF MATTER

Activity 2.4 Define each chemical property of matter and fill in the

blanks for each example given.

Name of the

Property Definition Examples

19. Combustibility

Glass is not …………….

Dry wood is ………..

combustible than wet

wood. ……….. fuels, like

coal, natural gas, and

gasoline, are combustible.

20. Reactivity with Water

Some substances, like

…………… are very

reactive with water, and so

they have to be stored in a

water-free environment.

Even the water vapor in the

air can cause a reaction so

these substances must be

stored under

………………..

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STATES OF MATTER

GLOSSARY - CONTENT SPECIFIC VOCABULARY – STATES OF MATTER

Read the definition and provide a suitable terms and translation for them from

the box

condense evaporate gas liquid boiling point mass

volume melt solid matter freeze melting point

TERM

(TRANSLATION)

DEFINITION

anything that has mass and occupies space

a measure of how much matter is in an object

(the amount of matter in an object)

matter in a state that has a definite shape and volume

matter in a state that has a definite volume but no

definite shape

matter in a state that has no definite shape or volume

to change slowly from liquid to gas

to change from liquid to solid

to change from gas to liquid

to change from a solid to a liquid

the space an object takes up

temperature at which a liquid becomes steam (vapor)

or gas

temperature at which a solid becomes a liquid

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Activity 2.5 Diagrams of the arrangement of particles

Activity 2.6 Classify the following characteristics into solids, liquids or

gases

Definite shape Changeable

volume

Hardness Molecules close and tidy

Changeable

shape

Definite volume Viscosity Molecules close and

untidy

Changeable

shape

Definite volume Expansion Molecules distant

Solid Liquid Gas

Solid Liquid Gas

Draw a simple diagram of the arrangement of particles

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Activity 2.7 Cloze test

Fill in the blanks. Some answers may be used more than once.

condense heat mass solid gas liquid matter

Everything that you are able to see, touch, smell, and feel is matter. Matter is

anything that has ……………. and takes up space. The amount of matter in an

object is called it’s ……………

………… can be classified according to its state. A …………. piece of matter

has definite volume and shape. A …………….. has no definite shape, but has a

definite volume. A …………….., such as oxygen, has neither a definite volume

nor shape.

When ………….. energy is added to matter, changes to its state may occur. For

instance, when a solid piece of ice is heated, it may melt, becoming a liquid.

When heat is added to a liquid, it can evaporate, becoming a ……………..

When heat is taken away, a liquid can freeze, becoming a ……………….. When

heat is taken away from a gas, it can ……………, becoming a liquid.

The following statements define certain terms used in connection with

changes of state.

The word define is a command word often used at the start of certain exam

questions. It means you must answer with a short, but complete, meaning of the

term.

Definitions use the words which or that to link the parts of the definition

together. For example, Melting is the process that takes place when a solid

turns into a liquid.

Activity 2.8 How to write a definition

Complete these first examples by pairing up the two parts of the sentence. Put

the letter that goes with each number in the box provided beneath the table. The

first example has been done for you. Once you have completed exercise, write

out the whole sentence for each definition to help you remember it.

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1 Freezing is the process

……….

A …… that can flow from one

place to another

2 Fluids are substances …….. B ……… which a solid turns into

a liquid

3 The melting point is the

temperature at ……..

C …….. that turns a liquid into a

gas

4 Boiling is a process …….. D ……. that turns a liquid into a

solid

5 Solidification is the

process…..

E ……that transforms a liquid into

a gas

6 Evaporation is the process

……

F ………that transforms a solid

into a gas

7 Sublimation is the

process……

G …….that transforms a liquid

into a solid

8 Condensation is the process

………

H ……that transforms a gas into a

liquid

1 2 3 4 5 6 7 8

D

……………………………………………………………………………………

……………………………………………………………………………………

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Activity 2.9 Fill the blanks for the names of phase transitions and

phases in the following diagram.

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PHYSICAL AND CHEMICAL CHANGES

Activity 2.10 Complete the following diagram by inserting words and

phrases from each list below.

Types: physical changes, chemical changes

Characteristics: new substances formed, no new substances form, little change

in temperature, large change in temperature, often a change in color, usually no

change in color, change is hard to reverse, change is easy to reverse

Examples: condensation, combustion, hard boil an egg, rusting, evaporation,

melting gold

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Activity 2.11 Fill in the blank spaces with either ‘Physical’ or

‘Chemical’

1. Boiling water is a ………………. change.

2. Bending a metal pole is a …………………change.

3. Boiling potatoes is a………………… change.

4. Cutting an orange is a ……………..change.

5. Cutting a sheet of paper is a …………………… change.

6. Baking cake is a ……………………. change.

7. Melting snow is a ……………………change.

8. Slicing a banana is a ……………change.

9. Molding shapes with play dough is a ………………… change.

10. Melting glass into different shapes is a …………………change.

11. Mixing a cocktail of fruit juice is a ……………… change.

12. Rusting of a metal gate is a ……………….. change.

13. Washing clothes with bleach leads to a ………………. change.

14. A ……………... change leads to the formation of a new chemical substance.

15. A ………… change does not lead to the change of the chemical composition

of a substance.

16. Adding baking powder to scrambled eggs is a …………….. change

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Activity 2.12 Determine if the following processes are physical or

chemical changes

a. boil - ……………………………………………………………………………

b. combustion - ………………………………………………………………….

c. condense -………………………………………………………………………

d. corrode - ……………………………………………………………………….

e. crumple - ……………………………………………………………………..

f. ferment - ……………………………………………………………………….

g. melt - …………………………………………………………………………

h. rust - ……………………………………………………………………………

i. crush - …………………………………………………………………………

j. freeze - ………………………………………………………………………….

k. oxidize - ………………………………………………………………………..

l. tarnish - …………………………………………………………………………

m. explode - …………………………………………………………………….

n. grind - ………………………………………………………………………..

o. rot - ………………………………………………………………………….

p. vaporize - ………………………………………………………………………

q. photosynthesis - ……………………………………………………………….

r. sublimation – …………………………………………………………………...

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Classification of matter Scientists classify matter by looking at the types of particles that it contains. The

particles can be single atoms. Or the particles can be groups of atoms joined

together, called molecules.

This diagram contains two different kinds of particles.

They are different kinds and shown shaded as different

colors.

Each particle is called a single atom.

This diagram contains only one kind of particle.

Each particle is made up of two atoms joined together.

Each particle in this diagram is a molecule.

What can you say about the particles shown in the following diagrams?

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Activity 2.13 Pure substances and mixtures

Write four examples of pure substances and four mixtures. Also write the

substances they are made up of.

Pure substances Mixtures The mixture is made up of

Activity 2.14 Pure substance and mixture

Look at the images and write down whether the following materials are a pure

substance or a mixture. In the case of a pure substance, state whether it is an

element or a compound.

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Use the following sentences choosing the appropriate expressions to give

reasons for your answer:

The

first

material

is

a mixture

because

it is

formed

by

one type of

atom

chemically bonded

The

second

an element several types

of atoms

not chemically

bonded The

third

a compound

…………………………………………………………………………………………

…………………………………………………………………………………………

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…………………………………………………………………………………………

…………………………………………………………………………………………..

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Activity 2.15 Classification of matter

Answer the questions below and then complete the diagram, which shows the

classification of matter by using the terms and connecting phrases in the table.

You can use a phrase or term only once. Then list examples of each type of

matter.

Terms Connecting phrases Examples

Atom

Compound

Element

Homogeneous mixture

Heterogeneous mixture

Matter

Mixture

Molecule

Pure substance

Substances with identifying set of characteristics

Substances combined without reacting Substances formed by combining

other substances

Substances that cannot be broken down any further

Mixtures which are uniform Mixtures that are not uniform The smallest particle of an element The smallest particle of many

compounds

Air

Aluminum

Calcium

carbonate

Candy bar

Carbon dioxide

Chocolate

Copper

Copper (II) sulfate

Cotton

Dirt (from a

garden)

Drinking water

Hydrogen

Oxygen

Paint

Salad

Silver

Sugar

Table salt

Sulfur

Glass

Distilled water

What are the similarities and differences between a compound and a

homogeneous mixture? (this is answered for you as an example):

A compound and a homogeneous mixture are similar because they are made of

more than one substance and look uniform

A compound and a homogeneous mixture are different because a compound has

chemically combined elements (always the same proportions) and a

homogeneous mixture is physically combined substances (elements or

compounds) evenly mixed.

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What are the similarities and differences between an atom and an element?

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What are the similarities and differences between a molecule and an atom?

……………………………………………………………………………………

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……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

What are the similarities and differences between a pure substance and an

element?

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……………………………………………………………………………………

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……………………………………………………………………………………

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…………………………………………………………………………………….

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E E E E

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Classification of Elements

Activity 2.16 Arrangement of elements in a Periodic Table

Use green, blue and red colors to show phases of elements. In the periodic

table above show solids with green background, liquids with blue background,

and gases with red background.

1

2

3

4

5

6

7

1

2

3

4

5

6

7

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The Names of the Elements

Activity 2.17 Where did names of elements come from?

As you look at your periodic table, you will recognize some of the more common

elements, but you will probably also notice that some elements have strange

names. Where did all of these names come from? You will find out as you work

through the exercises below.

Some elements are named after places. Write the name in English and

Russian, and the symbol of the element that is named after the place given in

each question.

1. Russia ……………………………………………………………………..

2. The country of France …………………………………………………….

3. The country of Germany…………………………………………………..

4. America:……………………………………………………………………

5. The country of Poland. ……………………………………………………

6. Scandinavia: ………………………………………………………………

7. The city of Berkeley:……………………………………………………..

8. The continent of Europe…………………………………………………

Four of the elements are named after planets. Complete the chart below for

the elements named after planets.

Element Name (Symbol) Planet Name

………………………………. ………………………….

……………………………….. …………………………

………………………………. ………………………….

……………………………… ……………………………

Many elements are named after famous scientists. The scientist’s last name is

used along with the ending “ium”. Write the element after each scientist

given.

1. Albert Einstein: …………………………………………………………….

2. Pierre and Marie Curie: …………………………………………………..

3. Enrico Fermi: ……………………………………………………………..

4. Alfred Nobel: ……………………………………………………………….

5. Dmitri Mendeleyev: ……………………………………………………….

6. Ernest Lawrence: ………………………………………………………….

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You’ve probably noticed that some of the names of the elements do not match

the symbols. That’s because some symbols are made from Latin name of the

element. Look up the symbol on the Periodic Table and see if you can match the

English name to the Latin name. Use each letter once.

English Latin Correct answer

1 Antimony A Argentum Antimony – Stibium

2 Copper B Aurum

3 Gold C Cuprum

4 Iron D Ferrum

5 Lead E Hydrargyrum

6 Mercury F Kalium

7 Potassium G Natrium

8 Silver H Plumbum

9 Sodium I Stannum

10 Tin J Stibium

11 Tungsten K Wolfram

Some elements named for mythological characters

1. ……………… named after Thor, the Scandinavian god of war.

………………. is used as a fuel for nuclear weapons.

2. ………………… —named after Titans, supermen of Greek mythology.

………………….. is a super-element because it is very resistant to acid.

3. ………………….. —named after the Scandinavian goddess of beauty,

Vandis, because …………..; compounds form such beautiful colors.

4. ………………. and ……………….. named after the mythological Greek

king, Tantalus, and his daughter, Princess Niobe. Like the king and his

daughter, ………………. and ……………. are often found together.

Some elements named for their properties

1. …………………… —from Greek chloros meaning “green.” ……………. is

a greenish yellow gas.

2. ……………… from Greek iodos meaning “violet.”

3. ………………. —from Greek argos meaning “lazy.” …………… is an

extremely unreactive gas, so it was thought too lazy to react.

4. ………………… from Greek kobold meaning “goblin” or “evil spirit.”

………… miners often died suddenly and unexpectedly, which was probably

due to ingesting arsenic found with the …………… ore in the German mines.

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Activity 2.18 Symbols of chemical elements

Write the symbol of the elements mentioned in each sentence.

1. Mercury is used in some thermometers …………………

2. Uranium provides us the fuel for nuclear power …………………

3. Bones and teeth are made mostly of calcium…………………..

4. Diamonds are made of carbon ………………….

5. Some balloons are filled with helium………………

6. We get the oxygen that we breathe from the air …………

7. Germs get killed by chlorine in swimming pools …………….

8. Our air is 78 percent nitrogen ……………

9. Magnesium is found in some heartburn medicine …………

10. Amethyst jewelry is made of silicon ……………….

11. Bananas are a source of potassium for the body………….

12. Sulfur is the main ingredient in gunpowder ……………….

13. Pennies are coated with copper ………………….

14. Tin is used to make foil and cans ………….

15. A healthy thyroid gland needs iodine ……………

16. Lead is a heavy metal that is toxic to humans ……………

17. Gold is one of a few elements that is found in its pure form ………..

18. Silver can be used to make mirrors …………..

19. Zinc is used to coat many objects made of steel ……………….

20. Sodium can be found in salt ………..

21. Magnets are made mostly of iron ………….

22. Phosphorus is used to make objects glow………

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Activity 2.18 Elements in some common compounds

Below is a list of the chemical formulas of some common compounds. Write

the name of the elements they are made of

1. Water H2O ………………………………………………………………

2. Table salt NaCl ……………………………………………………………

3. Sulfuric acid H2SO4 ………………………………………………………

4. Sand SiO2 …………………………………………………………………

5. Rust Fe2O3 ………………………………………………………………..

6. Baking soda NaHCO3…………………………………………………..

7. Photo developer AgCl ……………………………………………………..

8. Ammonia NH3 …………………………………………………………….

9. Fool’s Gold FeS2 ……………………………………………………….

10. Stomach Acid HCl ………………………………………………………

Activity 2.19 Symbols and names of elements

Symbols of the elements are used in the sentences below. Write the name of

the elements of the symbol used in the sentence in the space provided.

1. I ……………………. is used by campers to purify water

2. Mg ………………………. is used to treat skin rashes.

3. Some switches contain Hg ………………………

4. Some glass plates are coated with Au …………………

5. Some pots and pans are made of Al ………………….

6. Wire made of Ni ……………….. is used in toasters.

7. Some bowls and plates are made of Sn …………….

8. Pb ………………. is used to make television screens.

9. P ………………… is used by the body.

10. Some liquid soaps use K ………………

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11. Cu ……………… is used for paint on ships.

12. Zn ……….. is used to make brass.

13. Ca …………….. is used in building materials.

14. He …………….. is used in bar code scanners.

15. Some weapons are made from U…………………………

Activity Uses of Some of the Elements:

Choose your answers for questions 1-19 from the following list of elements.

Each element is used only once. If an element appears twice in the list, use it

twice!

aluminum carbon copper hydrogen iron mercury

uranium arsenic chlorine copper iodine tungsten

lead neon calcium chromium fluorine iron magnesium

1. What metallic element is sometimes used in flares and flashbulbs because

it burns with a bright, white light? …………………………………

2. What element is used to disinfect swimming pools?.................................

3. What element is needed for strong bones and teeth? …………………….

4. What element is found in liver and is needed to prevent anemia or “tired”

blood?..........................................................

5. What element is added to toothpaste and city water systems to help tooth

decay? ………………………………………………..

6. Which element is used to “paint” the skin to prevent infection from cuts

and scratches………………………………………………….

7. What element is used in bright, flashing advertising signs? ………………

8. What element is a liquid metal used in thermometers? ……………………

9. Which element is used for the shiny trim on cars? ………………………

10. Which element is used in light bulbs as a filament? ……………………

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11. Which element is used as rat poison and is found in the title of the murder

mystery “__________ and Old Lace”? ………………………………….

12. What element is found in the coins? ………………………………….

13. A diamond and your pencil lead (graphite) are made of this same

element………………….

14. Steel is formed when a little bit of carbon is added to this element. (The

carbon gives strength and hardness to the steel.) ………………………..

15. What element is used as a shield to protect people from radioactive

substances? ……………………………………………………

16. What element has the lowest density of all of the elements?

…………………..

17. What element was used to make the first atomic bomb? …………………

18. Which element is rolled into a foil found and used in your kitchen?

………………………

19. What element used to be mined in the Upper Peninsula of Michigan?

Several towns in the Upper Peninsula are named after this element, including

“………………. Harbor.”

33

ALLOTROPES Activity 2.20 Allotropes of carbon atom

Look at these two diagrams:

The first structure is carbon graphite and the second one is carbon diamond.

Are both structures formed by same balls? …………………………………………..

Are they identical? ………………………………………………………………

…………………………………………………………………………………..

What differences can you find? Complete this table with the following words:

layers longer length tetrahedral shape four equal three carbon atoms

Features C (diamond) C (graphite)

General

structure

Carbon atoms form four

covalent bonds in a

……………………..

Carbon atoms form four covalent

bonds in ……………………..

Number of

chemical

bonds

Each carbon atom is bonded to

………….. carbon atoms

Each carbon atom is bonded to

…………. In an hexagonal

pattern, in the same plain.

length of

chemical

bonds

All the bonds have the same

………………..

The fourth bond is ……………

than the others and is established

between the layers

34

“Classify in similarities and differences”

Using the phrases in the boxes complete the table similarities and differences

between C(diamond) and C(graphite)

Both of them are formed by carbon atoms

Each one has a different structure

The carbon atoms form covalent bonds

As a consequence of the different giant covalent structure, they have different

appearance, and different properties

They are elements

They have different color

Both of them are solids

They have different melting point...

They are represented by the same symbol but with a bottom specification

Similarities and differences between C(diamond) and C(graphite)

Similarities Differences

35

Physical appearance

Use the Internet to search for two photographs. One of them a diamond and

the other of graphite, and try to find the physical properties of both.

Carbon diamond Symbol:

Physical state:

Colour:

Melting point:

Uses:

Carbon graphite Symbol:

Physical state:

Color:

Melting point:

Uses

36

In some elements the atoms pair up:

Oxygen is an element like this. It is formed by two atoms. This particle is called

a molecule. It can be represented by a formula: O2

Symbol of element

O2 Number of atoms that form the molecule

Molecules of Oxygen, Hydrogen, Nitrogen, Fluorine, Chlorine, Bromine and

Iodine are diatomic: O2, H2, N2, F2, Cl2, Br2, I2

This is the model of an Oxygen molecule. It’s diatomic because is formed by

two equal atoms.

Look at this table. All of them are elements, but they have different structures:

Element Symbol Diagram

Aluminum Al

Mercury Hg

Helium He

Oxygen O2

37

Nitrogen N2

Carbon (graphite) C (graphite)

Carbon (diamond) C (diamond)

Tick the correct properties of all these elements

Properties Helium Oxygen Nitrogen Aluminum Mercury Carbon

(graphite)

Carbon

(diamond)

Formed by

molecules

with 2 atoms

formed by

only one

atom, without

any chemical

bond

A gas at

ordinary

temperature

A solid at

ordinary

temperature

A liquid at

ordinary

temperature

formed by a

metallic

structure

Formed by a

giant covalent

structure

38

What elements are solids at ordinary temperature?

……………………………………………………………………………………

……………………………………………………………………………………

What elements are liquids?

……………………………………………………………………………………

What elements are gases?

……………………………………………………………………………………

…………………………………………………………………………………….

What are the differences and the similarities between the models of the Carbon

diamond and graphite and the models of the other elements?

……………………………………………………………………………………

……………………………………………………………………………………

…………………………………………………………………………………..

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

…………………………………………………………………………………….

What are the similarities between Oxygen and Nitrogen?

……………………………………………………………………………………

…………………………………………………………………………………..

What are the similarities and the differences between Oxygen and Helium?

……………………………………………………………………………………

……………………………………………………………………………………

…………………………………………………………………………………….

What are the similarities and the differences between Oxygen and Aluminum?

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

What are the similarities and the differences between Aluminum and Mercury?

……………………………………………………………………………………

…………………………………………………………………………………….

39

COMPOUNDS

A compound is a substance that can be broken down into simple substances or

elements by a chemical reaction.

Compounds can be represented by a molecular formula.

A water molecule is formed by two Hydrogen atoms and one Oxygen atom. So,

its formula is H2O and it is a compound.

CO2, CH4; NaCl….. are compounds too.

Compounds have different properties to their constituent elements

Also a compound is a substance that is made up of two or more different

elements combined together chemically.

An element is a substance that cannot be split up into simpler substances by

chemical means.

Activity 2.21 “fill the gaps” with “elements” or “compounds”:

1. …………………… are substances that can be split up into simpler

substances by chemical means

2. ……………………. are substances that are formed by more than a kind

of atom.

3. ………………………..are substances that cannot be split up into simpler

substances by chemical means

4. ………………………are substances that are formed by a kind of atom.

Activity 2.22 “classify “these substances as elements and compounds

H2, O2; Hg, N2, Ar, C(graphite), CO2, CH4; NaCl (sodium chloride), H2O, NH3

(ammonia), Cu, Cl2, C2H6 (ethane), Fe2O3 (Iron (III) oxide) ; H2SO4 (sulfuric

acid); MgCl2 (magnesium chloride)

Elements Compounds

40

Comparing properties of elements and compounds You probably already know some of the properties of sodium chloride, it is the

salt used in cooking, at the table, and the main salt in seawater.

Properties of the compound sodium chloride, NaCl are compared with the

properties of the metal sodium and the non-metal chlorine below:

Substance Properties

Sodium

chloride

solid at room temperature, reacts with some elements, colorless,

melting point = 801°C

Sodium solid metal at room temperature, reacts readily with most non-

metal elements and with water, shiny silvery surface, melting

point = 98°C

Chlorine gas at room temperature, reacts readily with most metals and

nonmetals, yellow, melting point = –101°C

Activity: Sodium chloride, sodium and chlorine

Compare the properties of the compound, sodium chloride, with the properties

of the elements that it consists of.

1. What is the state of sodium chloride, sodium and chlorine at room

temperature?

............................. and …………. are both solids while ………… is a gas at

room temperature.

2. What colors are sodium chloride, sodium and chlorine?

Sodium chloride is …………..; sodium is ……….. and ………, ……… chlorine

is a …………. gas.

3. Compare the melting point of sodium chloride with the melting points of

sodium and chlorine.

Sodium chloride has a ……… melting point (MP) of 801°C, while sodium

has a ………. MP of 98°C and chlorine a ……….. ……… MP of –101°C

4. Compare the readiness of sodium chloride, sodium and chlorine to react.

Sodium chloride reacts with ………… ………; sodium reacts with ………..

……………. and ……………. . Chlorine also reacts with ……………

…………….

5. Are the properties of sodium chloride the same as those of sodium and

chlorine?

………… . Sodium chloride has …….. ……… properties from those of both

sodium and chlorine.

41

Activity: Calcium carbonate, calcium, carbon and oxygen

The table following shows the properties of a compound called calcium

carbonate CaCO3. Sea shells and limestone rock consist of calcium carbonate.

The table also shows the properties of the elements in calcium carbonate:

calcium, carbon and oxygen.

Substance Properties

Calcium

carbonate

white solid, doesn’t react with water but reacts with acid,

melting point = 1339°C

Calcium grey solid, reacts with water and acid, melting point =

842°C

Carbon black solid, doesn’t react with water or acid, melting

point =

3974°C

Oxygen colorless gas, doesn’t react with water or acid, melting

point = –219°C

Complete the sentences comparing the properties of calcium carbonate,

calcium, carbon and oxygen.

Calcium carbonate is ………. . Calcium is ………. Carbon is …….. and

oxygen has ……... That is, the substances are all different …………………

Calcium carbonate, calcium and carbon are all ……. whereas oxygen is a

…………… at room temperature.

Both …………. and …………. don’t react with water or acid. Calcium

carbonate reacts with acid whilst calcium reacts with …….. and ………...

There is a wide range of …………… points from –219°C to 3974°C.

The properties of the compound, calcium carbonate, are …… ……….. from

the ……………… of the elements it is composed of.

42

CHEMICAL FORMULA

The symbol of an element represents one atom of that element.

A subscript is a number written at the lower right corner behind the symbol of

an element. If there is more than one atom of the element, then a subscript is

used to indicate the number of atoms.

e.g., Cl2 = Chlorine molecule which contains 2 chlorine atoms

Parentheses - in some chemical formulas it is necessary to use parentheses. The

subscript outside the parentheses refers to all the elements inside the

parentheses.

Al(NO3)3 In this example there are: one Al (aluminum), three N (nitrogen), and

nine O (oxygen) atoms.

A coefficient is a number written in front of a chemical symbol and indicates the

number of atoms of that element or number of molecules

e.g., 3C = 3 carbon atoms

2H2O = 2 water molecules

Note: a coefficient multiples the number of atoms of each element in the

formula

2H2O = 4 hydrogen and 2 oxygen atoms

43

Sodium chloride is a compound. For each sodium atom (Na) there is one

chlorine atom (Cl). It can be shown as

Look at the drawings of these molecules. Draw lines to match them to the

correct formulae.

CO2

HCl

H2O

CH4

H2O2

44

Activity 2.23 Composition of compounds

Count the atoms present in the different compounds by using the coefficients and

subscripts.

K2CO3

2 potassium atoms

1 carbon atom

3 oxygen atoms

Total 6 atoms

Ba3(PO4)2

Na2CrO4

3 CaCl2

4 Al2(CO3)3

Pb(NO3)2

2 (NH4)2Cr2O7

45

The relative atomic and molecular masses

GLOSSARY - CONTENT SPECIFIC VOCABULARY

Read the definition and provide a suitable terms and translation for them from

the box

The relative atomic mass (Ar) of an element Mole

The relative molecular mass (Mr) The molar mass (M)

TERM

(TRANSLATION)

DEFINITION

is the average mass of an atom according to relative

abundances of its isotopes, on a scale where the mass

of one atom of is 12 exactly. It has no units

is the relative mass expressed in g and has units of

g/mole

is the sum of the relative atomic masses of the atoms

in the molecular formula.

is the amount of a substance

46

Activity 2.24 The molar mass of the following compounds

a. KNO3

M(KNO3) = A(K) +A(N) + 3A(O) = 39 + 14 + 3*16 = 101 g/mole

b. UF6

…………………………………………………………………………..

c. (NH4)2CO3

……………………………………………………………………………

……………………………………………………………………………

d. Ag2CrO4

……………………………………………………………………………

……………………………………………………………………………

e. H3PO4

……………………………………………………………………………

……………………………………………………………………………

f. Ca(NO3)2

……………………………………………………………………………

…………………………………………………………………………….

g. CH3COOH

……………………………………………………………………………

……………………………………………………………………………

h. PbSO4

……………………………………………………………………………

……………………………………………………………………………

i. Pb(NO3)2

……………………………………………………………………………

……………………………………………………………………………

j. Mg(OH)2

……………………………………………………………………………

…………………………………………………………………………..

k. Al2(SO4)3

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………..

47

Activity 2.25 Unknown element “X”

For each of the following compounds “X” is an unknown element. The

molecular mass of the compound is given in the bracket. Work out which

element X represents.

a) XO (40)

M(XO) = A(X) + A(O) = A(X) + 16 = 40

A(X) = 40-16 = 24, so X is Mg - magnesium

b) X2O (62)

……………………………………………………………………………

……………………………………………………………………………

…………………………………………………………………………..

c) XCl2 (110)

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

d) MgX2 (94)

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

e) CX2 (44)

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

f) XNO3 (63)

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

g) X(OH)2 (171)

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

h) X2O3 (188)

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

48

Percent composition is the percent by mass of each element found in a

compound.

Example: What is the mass percentage of oxygen in iron (III) hydroxide,

Fe(OH)3?

Step 1: Find the molecular mass of the compound.

1 Fe = 55.85 g

3 O = 3 × 16.00 g = 48.00 g

3 H = 3 × 1.008 g = 3.024 g

Molecular Mass Fe(OH)3 = 106.87 g/mol

Step 2: Find the percentage by dividing the part by the whole and

multiplying by 100.

W% (O) = 3 Fe(OH)g 87.106

O g 00.48 ×100 % = 44.91%

Activity 2.26 Percent composition by mass

Solve the following.

1. What is the mass percentage of magnesium in magnesium bromide,

MgBr2?

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

…………………………………………………………………………………..

2. What is the mass percentage of carbon in glucose, C6H12O6?

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

………………………………………………………………………………….

49

3. What is the mass percentage of zinc in of Zn3(PO4)2?

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

…………………………………………………………………………………..

……………………………………………………………………………………

4. What is the mass percentage of Cu in CuCO3?

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

5. What is the mass percentage of copper in CuCl2?

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

6. What is the mass percentage of silver in AgNO3?

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

7. Which has more aluminum by mass, Al2O3 or Al(NO3)3?

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

50

8. Why is knowledge of percent composition important in the mining

process?

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

…………………………………………………………………………………..

9. A class of compounds called sodium metaphosphates were used as

additives to detergents to improve cleaning ability. One of them has a molecular

mass of 612g. Analysis shows the composition to be 22.5% Na, 30.4% P, and

47.1% O. Determine the molecular formula of this compound.

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

…………………………………………………………………………………..

10. Glucose, one of the main sources of energy used by living organisms, has

a molecular mass of 180.2g. Chemical analysis shows that glucose is 40.0% C,

6.71% H and 53.3% O. Determine glucose’s molecular formula.

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

…………………………………………………………………………………..

51

The law of definite proportions states that regardless of the amount, a

compound is always composed of the same elements in the same proportion by

mass.

𝑊% 𝑜𝑓 𝑎𝑛 𝑒𝑙𝑒𝑚𝑒𝑛𝑡 = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑎𝑛 𝑒𝑙𝑒𝑚𝑒𝑛𝑡

𝑚𝑎𝑠𝑠 𝑜𝑓 𝑎 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑 ∗ 100%

Example:

Let us consider any compound, say carbon dioxide.

We know that it is made up of carbon and oxygen. Atomic mass of carbon is 12,

while that of Oxygen is 16.

So, basically, there are 12 grams of Carbon and 16 x 2 = 32 grams of Oxygen in

carbon dioxide.

The ratio of Carbon to oxygen would be: 12: 32 = 6: 16 = 3: 8.

The simple ratio is 3: 8. So, taking any grams of CO2, it will always contain 3

parts of Carbon and 8 parts of Oxygen. This will remain a fixed ratio.

If we take 50 grams of carbon dioxide, it will have

50 X 3/11 = 13.64 grams of Carbon and

50 x 8/11 = 36.36 grams of oxygen.

Activity 2.27 The law of definite proportions

Solve the following problems

1. A 20.0-g sample of sucrose contains 8.4 g of carbon. What is the mass

percentage of carbon in sucrose? Show your work.

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

52

2. Sucrose is 51.50% oxygen. How many grams of oxygen are in 20.0 g of

sucrose? Show your work

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

……………………………………………………………………………….

3. 78.0 g sample of an unknown compound contains 12.4 g of hydrogen. What

is the percent by mass of hydrogen in the compound?

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

……………………………………………………………………………….

4. How many grams of hydrogen are in 100.0 g of fructose, C6H12O6?

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

5. A 20.00 g sample of ordinary table salt contains 12.13g of chlorine.

Calculate the mass percentage of each element in salt.

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………...

6. A sample of baking soda contains 34.48 grams of sodium, 1.51 grams of

hydrogen, 18.02 grams of carbon and 72.00 grams of oxygen.

a) What is the total mass of the sample?

…………………………………………………………………………

………………………………………………………………………….

b) What is the mass percentage of each element in baking soda?

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

53

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