Shrinking balloons

hydrogen

air

After 1 week

After 1 week

Shrinking balloons The balloons have got smaller so

some of the gas they contain has escaped.

This means that the balloon must have holes in its surface.

Since the gas is escaping it must be made of tiny particles.

To escape these particles must be able to move.

Mixing substances Diffusion is the name for the

way in which one substance can spread through another.

Diffusion

After

Gas and gas

10 minutes

Coverslip

Brown gas

Diffusion

After

Liquid and liquid

2 days

Blue liquid

water

Diffusion

After

Solid and liquid

5 days

Blue crystal

water

Diffusion

After

Solid and jelly

1 week

Blue crystal

jelly

Solid, Liquid and Gas

Gas

Solid Liquid

Diffusion These

experiments tell us:

Gases

Liquids

Solids

Largerspacesbetweenparticles

Diffusion These

experiments tell us:

Gases

Liquids

Solids

Particlesmove quickly

Particlesmove slowly

Particles hardly move

Expansion and Contraction

When anything is heated it expands (gets bigger), and when it is cooled it contracts (gets smaller).

Phone wires are hung loosely, so that they will not break when they contract in winter.

Expansion and Contraction

Railway lines have gaps between them, so that they will not buckle and bend in hot weather.

The mercury in a thermometer expands and contracts so that we can measure temperature.

The bimetallic strip

Heat the bimetallic strip

The bimetallic strip bends

The bimetallic strip is made of two different metals.

When the bimetallic strip is heated both metals expand differently.

This makes the bimetallic strip bend.

The bimetallic strip is used in fire alarms and thermostats.

Compression

compressed

Solid

Liquid

compressed

Gas

compressed

Air pressure Air particles move quickly

around us. They hit us, and all other

objects, from all sides. This force on us is called air

pressure.

The water cycle.

steam (gas)

water (liquid)

water (liquid)

ice (solid)

gas

solid

liquid

evaporation

condensation

melting

freezing

liquid

Density In dense materials the particles

are packed closely together. Density is measured by dividing

mass by volume. Water has a density of 1 g/cm3. Any substance with a density of

more than 1 g/cm3 will sink in water.