How would you describe the structure ot an atom?

Up to GCSE it is a very small positive nucleus which has protons and neutrons, surrounded by negative electrons in shells or energy levels around it.

Protons have a charge of ##+1## and a relative mass of ##1## Neutrons are neutral (have no charge) and also have a mass of ##1## Electrons are negative (have a charge of ##-1##) and have a negligibly small relative mass ##(1/1840)##

The first energy shell contains ##2## electrons and all the ones after that contain ##8##.

Beyond GCSE we learn that electrons are arranged in 4 different orbitals named ##s, p, d## and ##f## which contain ##2, 6, 10 and 14## electrons respectively.

The "first shell", known at A-level and beyond as the "principal quantum level" has a ##s## orbital (which means a maximum of ##2## electrons)

The second quantum level has ##s and p## (which is a maximum of ##2+6## or ##8## electrons), the third has ##s, p and d## (which means it has a maximum capacity of ##18##) and the fourth has ##s, p, d and f## (which means it has a maximum electron capacity of ##32##).