1. THE PARTICULATE NATURE OF MATTER
Kinetic theory
DIFFERENCES BETWEEN SOLIDS, LIQUIDS AND GASES
PROPERTIES OF SOLIDS, LIQUIDS AND GASES:
Surface boundary Shape
Solid Property Have a surface boundary Fixed shape
Reason Strong forces of attraction between particles - Strong forces of attraction between particles in solids
: prevents particles from escaping : particles are held together in a fixed shape.
- The particles vibrate about fixed positions but do not move
from place to place.
Liquid Property Have a surface boundary Take the shape of their container
Reason The forces of attraction between the particles are The forces of attraction between particles in the liquid are
strong enough weaker compared to solids.
→ to prevent the majority of the liquid particles from → the particles slowly move from place to place
escaping and becoming a gas : the liquid can change its shape to fit the container
Gas Property No surface boundary Fill the container they are held in (have no fixed shape)
Reason Gas particles move at high speed The forces of attraction between gas particles are extremely
→ the particles have only very small forces of weak
attraction between them → the gas particles move at very high speeds, which is why
they fill the container
PARTICLE ARRANGMENT IN SOLIDS, LIQUIDS AND GASES
The particles are… Touching Touching Far apart
The arrangement is … Regular Irregular Random
The forces between the particles Strong or quite strong Less strong Non-existent
…
So the particles can… 1. 1. Vibrate to and fro 1. Move around 1. Collide with each other and
2. 2. Do not move apart 2. Slide past each other bounce away again
(why a solid has a fixed shape) (why a liquid can be (why a gas spreads)
poured) 2. They move with random
motion at high speeds
When you apply pressure... The particles cannot move any closer The particles can’t move Particles can move a lot closer
→ volume doesn’t change closer → the gas can be pushed into a
→ volume doesn’t change much smaller volume
MORE PROPERTIES
Solids
Liquids Gases
: have a fixed volume
: have a fixed volume : do not have a fixed volume
: ------------- shape
: do not have a fixed shape : do not have a fixed shape
: ------- high density
: have a moderate to high density : have a low density