West Lothian Council
Lorna C. Webster
1
The difference between elements and compounds
Read
You should already know from S1 and S2 that elements are
made from tiny particles called atoms. Each element only has
one kind of atom. For example a piece of gold only has gold
atoms, a piece of iron only has iron atoms and a test tube of
oxygen will only have oxygen atoms in it.
gold
oxygen
iron
You already know that new chemicals can be made when we
react chemicals together. This is because the atoms can bump
into each other and become joined together.
A substance called a compound is made when two or more
different elements join together. So if we had a strong enough
magnifying glass and we looked at a compound we might see
atoms like those shown below.
Write a heading and copy and complete the work below.
1. The tiny particles in elements are called _ _ _ _ _.
2. Each element has one/two types of atoms.
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3. Draw pictures to show the atoms in samples of gold, iron and
oxygen.
4. Atoms in oxygen are further apart because oxygen is a
solid/liquid/gas.
5. When chemicals react atoms j _ _ _ t _ _ _ _ _ _ _.
6. A compound is made when t _ _ or more e _ _ _ _ _ _ _ join
together.
7. Draw a picture to show what the atoms in a compound might
look like if we had a strong enough magnifying glass.
8. Copy the table below
Sample
A
B
C
D
E
element or compound?
Look at the display of models and use it to complete your table.
9. Think: How did you work out from the models whether the
sample was an element or a compound?
Read
It is easy to work out if a substance is an element or compound
if we can see the atoms but what if we only know its name?
Working out if a substance is an element or a compound from
its name is also easy. If the name is only one word we need to
look at a periodic table. If the word is on the periodic table
then the substance is definitely an element, if not the
substance is not an element – it will either be a compound or a
mixture.
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Look at the display called display 2 and make two lists under the
headings “elements” and “not elements”.
Making a compound
Read
A compound is a substance which is made up of two or more
different elements joined together.
Your teacher will show you how to make a compound by joining
metal elements and oxygen gas.
Write a heading and try the work below
1. Draw a diagrm of the experiment that your teacher
demonstrated.
2. Copy the table below and complete it to describe what
happened.
Name of metal
what happened when it
reacted with oxygen
Magnesium
Zinc
Copper
You are now going to do an experiment to make your own
compound.
Collect experiment card 1.10, follow the instructions on the
card and then continue the work in your jotter by compying ans
completing the statements3 -9.
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3. The names of the two elements in this experiment were
_ _ _ _ and _ _ _ _ _ _ _.
4. It was e _ _ _to separate the iron a _ _ _ _ from the
s _ _ _ _ _ _ atoms before you heated them.
5. Draw a labelled diagram to show how you heated the elements
together.
6. When the iron and sulphur atoms were heated together a
n _ _ s _ _ _ _ _ _ _ _ _ was formed.
7. After heating the iron and sulphur could n _ _ be easily
s _ _ _ _ _ _ _ _ with a magnet.
8. When heated the elements iron and sulphur j_ _ _ _ _ to for
a c _ _ _ _ _ _ _.
9. Copy and complete the sentences below by choosing the
correct words.
It was easy/hard to separate the iron and sulphur before we
heated it because it was a mixture/compound and the atoms
were/were not joined. After we had heated the elements we
could/could not separate the atoms because they had made a
mixture/compound and the atoms had joined together.
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Working out the names of compounds
Read
Compounds always have two parts to their names just like your
name has two parts (first and last name). The names of some
compounds are shown on the bottles below.
If two elements are joined together to make a compound the
name of the compound will end in –ide. In experiment 1.10, you
joined iron and sulphur together so the name of the compound
you made was iron sulphide.
Some compounds have names that end in –ite or –ate. This
means that the compound has been made from three elements
and one of them is always oxygen. For example the compounds
called copper carbonate contains copper, carbon and oxygen.
When you are working out the names of the elements in a
compound you should use a data book.
Write a heading and copy and complete the work below.
1. A compound has _ _ _ parts to it’s name.
2. A compound ending in ide contains one/two/three elemnets
3. If the name of a compound end in ite, it contains
one/two/three elements.
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4. If the name of a compound end in ate, it contains two/three
elements.
5. The element oxygen/hydrogen/carbon is always present in a
compound that has a name that ends with ite or ate?
6. Copy the table below and complete it by looking at display 3
(you should also use a data book for help with the names of
the elements).
The name of the compound
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what elements are in it?
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More about Mixtures
Read
Mixtures are made when different substances come together
without reacting. Mixtures are easy to separate because the
atoms have not joined. This is what happened when you mixed
the iron and sulphur together in experiment 1.10 and you could
separate the atoms with a magnet because they had not
reacted. This was a mixture of elements but we can make
mixtures of elements or mixtures of compounds or mixtures of
elements and compounds.
Mixtures of elements
To make a mixture of elements we could mix a tube of nitrogen
with a tube of oxygen. The elements mix but the atoms do not
join together.
A
Pure sample of
nitrogen
mixture of nitrogen
and chlorine
Pure sample of
chlorine
This means that mixtures and compounds are not the same. In
a compound the different atoms have joined together but in a
mixture of elements the different atoms are not joined
together.
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Write a heading and try the work below
1. A mixture is made substances come together without
r _ _ _ _ _ _.
2. Is it easy/hard to separate a mixture.
3. Explain your answer to question 2.
4. Copy the pictures on page 8 to show what happens when
nitrogen and chlorine atoms are mixed.
5. Copy the diagrams and the sentences below
A
Picture
Picture
Picture
Picture
B
C
D
___ shows a pure element.
___ shows a mixture of elements.
___ shows a pure compound.
___ shows a mixture of compounds.
6. Collect a copy of the “pure versus mixtures” sheet, fill it in
and stick it into your jotter.
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Separating mixtures
Read
It is easy to separate mixtures because the
substances that are present are not joined
together. We can use different procedures
to separate mixtures. You have already used
a magnet to separate iron from sulphur but
this only works for magnetic metals. The
main ways we separate mixtures are by using
experiments called filtration, evaporation
and distillation.
Filtration is a technique that is used to separate solids from
liquids.
Evaporation can be used to remove water from a solution.
Distillation can be used to separate a mixture of different
liquids.
Watch your teacher demonstrate how to separate water and
food colouring in a distillation experiment.
Write a heading and try the work below
1.
It is easy/hard to separate a mixture because the
substances are/are not j _ _ _ _ _ together.
2. Using the information you just read, write down the three
main experiments for separating mixtures.
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3.
4.
5.
The method would you use to separate
a) a solid from a liquid is _______________.
b) water from a solution is _____________.
c) a mixture of different liquids is _____________.
Collect a diagram of the distillation demonstration and
stick it into your jotter.
Write in the following labels to the diagram.
Pure
water
6.
7.
8.
9.
Bunsen
burner
Mixture of food
colouring and water
When the mixture in the flask was heated it started to
b___.
When boiled, the water turns into s_ _ _ _ and travels
through the cold condenser where it c _ _ _ _ down and
turns back into a l _ _ _ _ _. It can then be collected in
the beaker at the end.
How did you know that the water and the food colouring
had been separated?
Copy and complete the sentences below by choosing the
correct word.
A mixture of liquids can be separated by distillation
because the liquids have different boiling/melting points.
You are now going to try to separate a mixture of salt, sand and
water using filtration and evaporation. Collect experiment card
1.2 and follow the instructions on the sheet before you
continue with the work below.
10. Collect the sheet called filtration and cut out each
diagram. Beside each diagram write down what you did for
that part of the experiment.
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11.
Explain in your own words how you separated the sand from
the mixture?
12. The sand did not pass through the filter paper as the sand
particles are too big/small.
13.. Describe in your own words how you separated the water
from the salt.
Air
Read
You should already know that air is a mixture of different
gases. Most people think that oxygen makes up most of the air
because we need it to breathe but oxygen is only about 20% of
the air. Most of the air is nitrogen. Nitrogen is about 80% is
the air. There is a little carbon dioxide in the air too – there
must be because we breathe it out!
Write a heading and try the work below
1. Air is not a pure gas as it contains a mixture of o _ _ _ _ _ ,
n _ _ _ _ _ _ _ and c _ _ _ _ _ d _ _ _ _ _ _.
2. Why do most people think that oxygen makes up most of the
air?
3. Air contains approximately :
a)
_ _ % Nitrogen.
b)
_ _ % Oxygen.
4. Explain why air also contains some carbon dioxide.
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You are now going to carry out
some tests on oxygen, nitrogen
and carbon dioxide. Copy the
table below for your results
before you start.
Name of gas
what happened to
the glowing splint
what happened to
the limewater
Oxygen
Nitrogen
Carbon dioxide
Collect experiment card 1.3 and follow the instructions.
Complete your table as you go along. Then continue with the
following work.
5. Describe how you do a glowing splint test on a test tube of
gas.
6. Describe how you do a limewater test on a test tube of gas.
7. Collect a copy of the “mixtures of gases sheet”, complete it
and stick it into your jotter.
8. You know that air contains oxygen but if you hold a glowing
splint in air it won’t relight. Explain why you think that the
test for oxygen is not positive in air.
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