1. Element, Compound and MIXTURE SELF-TEST
Which of the
pictures shows
a model of an
element?
What is an element?
Where are all the elements listed?

2. two elements The Periodic Table lists all the elements.
An element contains one type of atom only.
It is a simple substance that cannot be split
into simpler substances by chemical means.
two
elements

3. Which of the pictures above represent an ELEMENT? There are five!j h d e f g i
Which of the pictures above represent an ELEMENT?
There are five!
see next page for answers

4. Answer : a,e,f,g and j are all elements, because the particles in them are identical (The same size and colour.)
b,c,d,h and i are compounds.
The picture below shows an experiment to find the percentage of oxygen in the air.
gas syringe copper turns to
copper oxide

5. Copper metal is heated in 100 cm3 of air.
What do you see happening to the copper?
What happens to the volume of air in the syringes and why?
Can you write an equation for the reaction that happens?

6. The copper turns from coppery pink to black.
This is because the copper reacts with oxygen in the air and turns to black copper oxide
The volume of air in the syringes changes from100cm3
to 79cm3. This is because all the oxygen in the air joins to the copper and so the volume of air that remains is everything that is not oxygen. If 79% is not oxygen, then 21% of air is oxygen.
copper + oxygen copper oxide

7. The Composition of Air can also be Determined using the rusting of Iron
The iron is trapped in 50cm3 of air.
As the iron rusts, the oxygen in the air joins to it.
iron + oxygen iron oxide
21% of the air has been used up, so water rises up the tube by 21%.
It then stops rising as there is no more oxygen to join to the iron.
You must remember the percentages of 4 gases in air
carbon dioxide %

8. a d b e c f The picture shows the laboratory preparation of oxygen.
Can you name the pieces of equipment that are labelled?
The answers are on the next page.

9. a d b e c f The laboratory preparation of oxygen.
tap funnel b
conical flask c
delivery tube d
gas jar e
beehive shelf f
trough
The laboratory preparation of oxygen.
Now name the two chemicals that are used.
One generates the oxygen.
The other is a catalyst - what is a catalyst?

10. Hydrogen peroxide generates the oxygen.
Manganese (IV) oxide is the catalyst.
A catalyst speeds up a chemical reaction but is not chemically changed itself in the process.
Questions
This method of collection is called DOWNWARDS DISPLACEMENT of WATER
Why does the first gas jar collected contain very little oxygen?
What is the test for oxygen?

11. The first gas jar contains most of the
air that was in the flask to start with.
so it contains very little oxygen
The test for oxygen is that it
relights a glowing splint.

12. Think of three Uses for Oxygen
Remember that a use is something we might go out and buy some oxygen for, so just breathing will not do.

13. Possible Answers to Uses of Oxygen :
1. Making a hot flame for welding -
oxy-acetylene welding.
2. Oxygen to assist breathing in hospitals.
3. Oxygen for breathing in space.
4. Oxygen to assist breathing under water.
5. Oxygen to assist breathing for firemen.

14. Here are four different elements burning in oxygen. 1 3 2
Here are four different elements
burning in oxygen.
Which is which? What products are formed? 4

15. 4 2 2 2 2 2 1 2 3 1. Sulphur burning 2. Carbon burning
sulphur + oxygen sulphur dioxide
S O SO2
2. Carbon burning
carbon + oxygen carbon dioxide
C O CO2
3. Magnesium burning
magnesium + oxygen magnesium oxide
4. Iron burning
iron + oxygen iron oxide
Some oxides are acidic and some are alkaline or basic. Which is which? 4

16. conduct electricity brittle conducts heat malleable shiny matt
Metal oxides like magnesium oxide or iron oxide
are alkaline or basic (red litmus turns blue).
Non-metal oxides like carbon dioxide or sulphur dioxide
are acidic (blue litmus turns red).
You need to know the differences in physical properties
between metals and non-metals.
Sort the following into properties of metals and non-metals.
does not conduct
electricity
variable colour
conduct electricity
brittle
conducts heat
malleable
shiny
silver
not attracted to
a magnet
matt
sonorous

17. a magnet except iron nickel and cobalt
METAL NON-METAL
conduct electricity
variable colour
malleable
does not conduct
electricity
shiny
brittle
silver
sonorous
matt
not attracted to
a magnet
not attracted to
a magnet except iron nickel and cobalt
conducts heat

18. Which of the pictures above represent a COMPOUND?j h d e f g i
Which of the pictures above represent a COMPOUND?
There are five!
You must know the definition of a compound and a mixture see next page for answers

19. A compound is made of two of more elements chemically combined together.
A mixture is made of two or more substances not chemically combined together.
The compounds are :
Notice that they all have atoms (circles) that are different, joined to each other. They may be different in colour or size or both. h d b c i