Solid
A solid has a fixed volume and shape. Two examples
of a solid are shown below.
Metal
Wood
This is an example of how atoms are arranged in a solid
Liquid
A liquid has a fixed volume but no fixed shape. It will
take the shape of the container it is in.
Milk
Ice cubes
This is an example of how atoms are arranged in a liquid
Gas
No fixed shape or volume. The gas will spread to fill the
volume and shape of the container.
Bromine Gas in a jar.
Fluorine gas in a jar.
This is an example of how atoms are arranged in a gas
Melting
This is when a solid melts and changes into a liquid.
For example, a chocolate bar melting into liquid chocolate on a
hot sunny day
Heat from the sun
Freezing This is when a liquid freezes and changes into a
solid
For example, when water is put into ice cube trays in the
freezer. It turns into a solid, ice.
Put tray in freezer
Water
Condensation
Water freezes.
Ice
This is when a gas changes into a liquid.
For example the steam from a shower ( gas ) changes into
condensation on a mirror. ( water/ liquid )
Steam
Water on Mirror ( Condensation )
Evaporation This is when a liquid changes into a gas.
For example, water in a kettle that changes into steam when
the kettle boils.
Water in Kettle
Steam from kettle
Particles Everything is made up from particles. The
particles are too small to see without the use of a powerful
microscope.
The simplest particles are called atoms. Atoms are the
simplest particles known from which everything is made.
When 2 or more atoms join together they form a
molecule
Diffusion
This is when one type of particles moves through another
type of particles. Diffusion will only take place when the
particles are in a liquid or gas state.
Diffusion can not take place in solids. This is
because they are not free to move.
The above diagram is an example of perfume fumes
spreading through the air. The perfume fumes will slowly
leave the bottle and start to spread through the air.
Eventually allowing us to smell the perfume with our nose.
This example is a perfume gas diffusing through the air
(gas).
The above example is of a coloured ink (liquid) diffusing
through water (liquid). At first the ink particles are all
together but they will slowly spread out (diffuse)
Diffusion:
Is fastest in a gas as the particles are moving faster, i.e. have more
energy and are more spread out.
Is slower in a liquid as particles are closer and aren't moving as fast.
It doesn't occur in solids as particles are held in position.
Expansion
Solids, liquids and gases expand (take up more room) when heated.
Expansion in a solid shown below
Heat
This is due to the particles moving faster and further apart as they gain
more energy. Expansion in a solid requires most energy, while
expansion in a gas requires least energy.
Contraction
When cooled, solids, liquids and gases contract (take up less room) as
particles move closer.
Cooling
A bimetallic strip is made from two strips of different metals
joined together.
A bimetallic strip bends when heated since one metal
expands ( particles move apart ) more than the other.
Some fire alarms and thermostats use bimetallic strips.