1. Particles, solids liquids and gases

2. What are the three states of matter?
At any given temperature, all substances exist in one of the three states of matter.
solid
liquid
gas

3. melting evaporation freezing condensation
Changes of state
Each change of state has a special name:
melting
evaporation
ice
water
steam
freezing
condensation

4. All substances are made up of particles.
The differences between solids, liquids and gases can be explained by looking at the particles.
All substances are made up of particles.
The particles are attracted to each other. Some particles are attracted strongly to each other, and others weakly.
The particles move around. They are described as having kinetic energy.
The kinetic energy of the particles increases with temperature.

5. What are the properties of solids?
have a high density, as the particles are packed very closely together
cannot be compressed because there is very
little empty space between particles
have a fixed shape because the particles are held tightly together

6. What are the properties of liquids?
have a fairly high density because the particles are close together
cannot be compressed because there is very little empty space between particles
take up the shape of its container because the particles can move
can diffuse because the particles are able to change places.

7. What are the properties of gases?
have a low density because the particles are spaced far apart
can be compressed because there is space between particles
have no fixed shape because the particles move about rapidly in all directions
can diffuse because the particles are able to move in all directions.

8. Melting point and boiling point
The temperature at which a substance changes from a solid to a liquid is called its melting point (or freezing point).
What is the melting point of pure water?
The temperature at which a substance changes from a liquid to a gas is called its boiling point.
Solids, Liquids and Gases Worksheet 1 accompanies this slide.
What is the boiling point of pure water?
What state is water at 25 °C, 300 °C and 100 °C?

9. Solid liquid or gas?
To work out whether a substance is a solid liquid or gas at room
Temperature you need to know….
Room temperature ( normally 20 oC )
The melting point of the substance
The boiling point of the substance
Melting point
Boiling point
Physical state at 20 0C
-30
liquid
220
125
400
Solid
-85 14
Gas
-123
-82
Gas

10. Solids, liquids and gases: which one?

11. Expansion When substances are heated, they get bigger… they Expand..
When substances cool down, they get smaller… the Contract
We cannot stop expansion.. But we can let it happen without things
going wrong!!
Power lines
Bridges
Railway
lines