1. By:
Devinda V.S
PARTICLE MODEL

2. In our world, matter exists in three states:
 Solid
 Liquid
 Gas

3. Solid
o Strong forces hold the particles together
o The particles only move a little
o They do not change position, but vibrate to
and fro in one position

4. Liquid
o The forces that hold the particles together
are weaker than in solids
o The particles can change position by sliding
over each other

5. Gas
o The forces holding the particles are very small
o The particles can travel in all direction

6. Changes in Temperature
Solid
Condensation
Liquid Gas
Evaporation

7. Changes in Solids
 When a solid is heated, it expands and when
it cools it contracts.
E.G
Railways:
There are gaps between the end of the rails. In
hot weather, the rail will expand and will
buckle up.

8. Changes in Liquids
 When liquids are heated, they expand much
more than solids for a given temperature.
E.G
When water get hot, it expands and rises up
the glass tube. While when the water is
cool, the level of the water in tube falls

9. Strange fact about water!
 When water cooled, it expands again when
it’s temperature drops below 4 degree
celcius.
 After 4 degree celcius, it will start to expand
until it reaches 0 degree celcius.

10. Changes in Gas
o Gases expand when they are heated
o Contract when they are cooled
E.G.
Hot air balloons:
When the air in the balloon is heated, it expands and
fills the balloon. The density of the air falls and it
becomes less dense than the air around it. The
surrounding area exerts an upthrust force which is
greater than the weight on it.

11. Thank You
For
Paying
Attention
!!!