Atoms is the smallest particle of a chemical element that can take part in a chemical reaction without being permanently changed. Every atom is made of only three different particles: protons, neutrons and electrons. The protons and neutrons are lumped together in the middle forming a nucleus and the electrons whizz around the outside.
There are only 111 different atoms in the whole Universe. About 92 occur in nature, the rest only exist in laboratories and the heart of exploding stars.
