Solids, liquids and gases

Particles can be atoms, molecules or ions. Particles behave differently in solids, liquids and gases. The particle model explains the differences between solids, liquids and gases.

Changes of state

Solids, liquids and gases change state when they are heated or cooled. Processes such as evaporation and boiling change the state of substances

Gas pressure

Pressure in gases is caused by particles colliding with the walls of the container.

What is water?

Learn about water in this KS3 guide.

5 Classroom videos

We have a selection of great videos for use in the classroom