There are three main states ... matter: solid, liquid and gas. When a substance changes state, this is a physical change because no new substances are produced and the change is reversible. The ...

Matter is made up of small particles called atoms. Atoms can exist on their own or together as molecules. Atoms are very small and around 100,000,000 of them end to end would measure 1 centimetre.

The focus is that matter, whether solid, liquid, or gas, is made up of particles ... On the Activity Sheet, have students describe what happens during the dissolving process when water dissolves salt.