CHEMISTRY ACTIVITY BOOK INTRODUCTION TO CHEMISTRY. MATTER.
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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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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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?
……………………………………………………………………………………
……………………………………………………………………………………
……………………………………………………………………………………
……………………………………………………………………………………
……………………………………………………………………………………
……………………………………………………………………………………
………………………………………………………………………………….
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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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