Structure of the atom

Protons, neutrons and electrons

Atoms are very small, they have a radius of around 1 × 10^-10 metres.

The modern view of the atom is of a nucleus containing protons and neutrons with smaller electrons orbiting outside the nucleus.

Each particle has its own charge and its own mass.

Relative chargeRelative mass Proton +1 1 Neutron 0 1 Electron -1 Close to 0 (1/2,000)

Mass number and atomic number

Protons and neutrons are the heaviest particles in an atom and as a result they make up most of the mass of the atom. The mass…