The atom
An The smallest part of an element that can exist. is made up of a small nucleus, containing protons and neutrons, which is surrounded by orbiting electrons.
Inside the nucleus
Subatomic particle with a positive charge and a relative mass of 1. The relative charge of a proton is +1. are positively charged and have mass.
Uncharged subatomic particle, with a mass of 1 relative to a proton. The relative charge of a neutron is 0. have no charge (are neutral) and have a similar mass to a proton.
Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons. are negatively charged and have mass - although they are substantially smaller than protons and neutrons.
Protons and electrons have exactly the same size of charge, but opposite charge as each other.
This means, that in the first diagram above (a helium atom) there are two protons and two electrons. Therefore, there are two positive charges and two negative charges and so the positive and negative charges cancel each other out.
