Structure of the atom

Everything in the world is made up of atoms. The structure of the atom is what gives an element its chemical and physical properties.

Atoms are made up of three smaller particles called electrons, protons and neutrons.


Negatively charged particles that spin around the positive centre of the atom in circles called energy levels. Their mass is so small it is nearly zero.


Positively charged particles that are contained in the nucleus of the atom (the centre) they have a mass of 1amu (atomic mass unit).


Particles with no charge are also contained in the nucleus of the atom. They too have a mass of 1amu.

The structure of an atom. In the middle is a nucleus containing protons and neutrons. There are energy levels around this with electrons on these various levels.

The nucleus has an overall positive charge as it contains the protons.

ElectronApprox 0-1Energy level
Proton1 amu+1Nucleus
Neutron1 amu0Nucleus

Every atom has no overall charge (neutral). This is because they contain equal numbers of positive protons and negative electrons. These opposite charges cancel each other out making the atom neutral.