1. Kinetic Model of Matter

2. State of Matter
Matter is made up of a tiny particles called atoms and molecules. These particles are much too small to be seen by human eyes.
Ice, water and steam are three different states of matter of the same material.
The three states of matter are called solid, liquid and gas.
Kinetic Model of Matter

3. Solid Properties Distance between molecules
Fixed shape and fixed volume
Not compressible
Does not flow easily
Distance between molecules
The molecules are arranged close together in a regular pattern.
Solids cannot be compressed because the molecules are arranged closed together and there is little space between them.
Kinetic Model of Matter

4. Forces between molecules/ Motion of the molecules
There are balanced forces between the molecules which hold them in fixed positions.
The molecules can only vibrate about their fixed positions alternately attracting and repelling one another.
The strong attractive forces prevent the molecules from leaving their positions while the repulsive forces which act when they are too close to each other prevent them from collapsing. This explains why a solid has a fixed shape and a fixed volume.
When a solid is heated, the molecules gain energy and vibrate. The separation between molecules increases slightly and the solid expands.
Kinetic Model of Matter

5. Liquid Properties Distance between molecules
Fixed volume but no fixed shape
Assumes the shape of the container which it occupies
Not easily compressible
Flows easily
Distance between molecules
The molecules are not arranged in a regular pattern and are slightly further apart than in solids.
Liquids cannot be compressed as the molecules are close together and there is little space between them.
Kinetic Model of Matter

6. Forces between them/ Motion of the molecules
The molecules also vibrate to and fro, alternately attracting and repelling one another with forces which can be just as strong as those in solid.
Though there is still forces between the molecules, they are not held in fixed position. Because of this, the molecules move among one another throughout the liquid. That is why liquids flow and take the shape of their container.
The attractive forces between the molecules make it difficult for the molecules to leave the liquid and thus liquids have a definite volume.
When a liquid is heated the molecules vibrate and move about vigorously. Thus the liquid expands slightly only to a very slight extent.
Kinetic Model of Matter

7. Gas Properties Distance between molecules
No fixed shape and no fixed volume
Assumes the shape and volume of its container
Highly compressible
Flows easily
Distance between molecules
The molecules are far apart.
A gas can be compressed because the molecules are sparse and there is a lot of space between them.
Kinetic Model of Matter

8. Forces between them/ Motion of the molecules
The molecules move randomly at high speed, colliding with one another and with the walls of the container.
The intermolecular forces act only at moments of collision. Otherwise, the molecules are so far apart the intermolecular forces become negligible. Therefore, a gas is free to fill a container completely.
Kinetic Model of Matter

9. Brownian Motion
Brownian motion is named after Scottish botanist Robert Brown who first observed it in 1827.
He used a microscope to study tiny grains of pollen suspended in water.
He noticed that the grains were constantly moving in a random manner.
Kinetic Model of Matter

10. The smoke particles are seen to move continuously and haphazardly.
Brownian motion can also be seen when using a microscope to look at smoke particles floating in the air.
The smoke particles are seen to move continuously and haphazardly.
Kinetic Model of Matter

11. In 1905 Einstein was able to explain how Brownian motion takes place.
He suggested that the irregular or random motion of smoke particles was the result of smoke particles being hit by unseen, fast moving air molecules.
Hence Brownian motion provides evidence of the movement of molecules.
Kinetic Model of Matter

12. Kinetic Model
The kinetic theory of matter states that all matter is made up of a large number of tiny atoms or molecules which are in continuous motion.
The existence of particles in continuous motion has been demonstrated by Brownian motion and diffusion.
Kinetic Model of Matter

13. Motion of Molecules and Temperature
In Brownian motion demonstration we can see that when the temperature is higher, the motion of smoke particles in the air become more vigorous.
This is because the surrounding air particles are moving faster and hitting the smoke particles more frequently and with greater force.
When temperature increases, thermal energy is transferred to the molecules and the molecules gain kinetic energy. Hence the molecules move faster.
Kinetic Model of Matter

14. Motion of Molecules and Pressure
When randomly moving gas molecules hit the wall of a container they exert a force on the wall.
As the pressure is defined as force per unit area, the force acting in the container gives rise the gas pressure.
Kinetic Model of Matter

15. Pressure against Temperature
For fixed mass of gas at constant volume;
As temperature of gas in container increases, the molecules move faster and hit the walls more frequently and more violently.
Gas pressure increases with gas temperature and vice versa at constant volume.
Kinetic Model of Matter

16. Volume against Temperature
When temperature of the gas container increases, the molecules move faster and hit the walls more frequently and with greater force.
This causes the pressure to increase.
At constant pressure, the volume of gas increases with increasing temperature and vice versa.
Kinetic Model of Matter

17. Pressure against Volume
If we half the volume of container, the number of molecules hitting the wall in one second will also be double.
At constant temperature, gas pressure increases when volume decreases.
Kinetic Model of Matter