1. Section 3
The Nature of Matter

2. Particle Theory of Matter
Matter is made up of extremely tiny particles.
These tiny particles may be molecules or ions.
A model of water dioxide
Molecules of the same substances are the same.
A model of carbon dioxide
Molecules of different substances are different.

3. Kinetic Theory of Matter
Gas particles are very far apart from each other.
They move at high speeds.

4. Kinetic Theory of Matter
Liquid particles are much closer.
They are moving continuously.

5. Kinetic Theory of Matter
Solid particles are close together in a regular pattern.
They cannot move from one place to another place.
Solid particles are vibrating about their positions all the time.

6. Experiment
To show that ammonia molecules and hydrochloric acid molecules are moving.
Procedure
1. Set up the apparatus as shown above.
2. Leave the apparatus for some time and observe.

7. Experiment
To show that ammonia molecules and hydrochloric acid molecules are moving.
Result

8. To answer the questions on the next page, you must imagine that the gases are made of tiny particles

9. Ammonia solution
White fume
Hydrochloric acid
Question
What happens when the hydrochloric acid particles met the ammonia particles?
Form white fume
Are the particles of the two substances moving?
yes
Do they move at the same speed? No
If the whole glass tube is warmed, do you think it takes a longer or shorter time for any change to be seen?
It takes a shorter time to form the white fume because...
Particles move faster at higher temperature

10. Ammonia solution
White fume
Hydrochloric acid
The above experiment shows that both ammonia and hydrochloric acid diffuse.

11. Diffusion Diffusion is the spreading out of a substance.
Particles of matter move from one
place to other places.
Why does diffusion occur?
Is the rate of diffusion equal to the speed of moving particles?
The speed of diffusion is
much smaller
Collision between the particles
slows down diffusion rate.
Why?
The possible path of a gas particle

12. Diffusion of bromine gas
Experiment A
Diffusion of bromine gas
Procedure
1. Place 2 drops of bromine into the gas jar and cover it immediately.
2. Observe how the bromine spreads by noting the colour.
gas jar
cover
bromine liquid
Question
1. How far has the bromine spread?
2. Can you explain how the bromine diffuses (spreads)?

13. B. Diffusion of solid in liquid
Procedure
1. Place a copper sulphate crystal into 75 cm3 of cold water.
2. Place another piece into the same volume of hot water.
3. Leave the two beaker for about 20 minutes and observe.
beaker
water
copper sulphate crystal

14. B. Diffusion of solid in liquid
Question
1. Why did we use a coloured solid?
2. Had diffusion of the coloured solid particles occurred?
3.Is diffusion faster in cold water or hot water?
4. Is diffusion faster in a liquid or in gas?
1. We can observe the diffusion of a coloured matter.
Yes
Diffusion is faster in hot water
Diffusion is faster in liquid

15. Change of States
Gas
Solid
Liquid
Example
Steam
Ice
Water

16. explained by kinetic theory
Change of States:
explained by kinetic theory
Heat energy is given to solid particles which then move faster
Solid
Liquid
Heat energy is taken away from liquid particles which then move slower
Heat energy is given to liquid particles which then move faster
Liquid
Gas
Heat energy is taken away from gas particles which then move slower

17. Go to section 3b