Understanding States of Matter and Changes of State

boiling

Water in a pot boils when it reaches a temperature of 100°C.

compressible

Gases can be compressed easily because the particles are separated by a lot of empty space.

condensation

When a gas condenses, the particles lose energy, slow down and move closer together.

deposition

In winter, water vapour in the air can turn directly into solid ice crystals on car windows as the particles lose energy.

evaporation

When a liquid evaporates, particles at the surface gain energy, speed up and spread apart to fill the surrounding space.

fluid

Liquids and gases are fluid because the particles move around each other.

freezing

When a liquid freezes, or solidifies, the particles lose energy, slow down and become held in fixed positions.

gas

Particles in gases move quickly and spread apart to fill the space in a container.

incompressible

Solids and liquids are usually incompressible because the particles are already close together.

liquid

A substance with a fixed volume that flows and changes shape.

matter

Any substance that takes up space and has mass.

melting

During melting, particles gain energy and begin to move around each other.

particle model

The idea that all matter is made up of tiny particles.

rigid

Unable to bend, flow or change shape.

solid

A substance with a fixed shape and volume.

solidification

A change of state from liquid to solid.

sublimation

A change of state from solid to gas.

water vapour

Water vapour is an invisible gas in air.

states of matter

The most familiar states of matter are solid, liquid and gas, but there are others.

gas to solid

A change of state from gas to solid.

gas to liquid

A change of state from gas to liquid.

liquid to gas

A change of state from liquid to gas at the surface of a liquid.

Fixed Volume

A substance has a fixed volume if the amount of space it takes up doesn't change, even if you move it to a different container or change its shape.

fixed shape

A substance has a fixed shape if it keeps its form even when you move it or try to change it.