Inside Atoms All matter is made up of atoms. Atoms are made up of subatomic particles: protons, neutrons and electrons. The protons and neutrons are tightly packed in the centre of an atom together from the nucleus of the atom. The electrons move rapidly around the nucleus. Subatomic particle Symbol Relative charge Relative mass Inside the nucleus

Measurement Physical properties SI Units Other Common Units Common measuring apparatus Name Symbol time second s hour (h) minutes(min) day digital stopwatch analogue stopwatch mass kilogram kg gram(g) tonne(t)