Atoms have a small central nucleus made up of protons and neutrons around which there are electrons.

Neutron - Relative Mass 1 Relative Charge 0

Proton - Relative Mass 1 Relative Charge +1

Electron negligible -1

The Hairy Bikers Experiment

The scientists use hairy bikers to demonstrate what an atom looks like.

When the bikers arrive, note how the rings that they form with their motorbikes show how the electrons orbit the nucleus and gradually fill up each shell around that nucleus until they finish with Neon as a full shell.

Exam tips: Learn how to represent all the partially filled shells up to Calcium and the maximum number of electrons that can occupy each shell.

Exam Questions:

• Draw the electron arrangement for the following elements. Example Sodium atomic number 11 has an arrangement of 2,8,1
• Draw the electron arrangement for Beryllium atomic number 4, Aluminium atomic number 13 and Potassium atomic number 19.