Topic 3 Molecules

A molecule is formed when two or more atoms are bonded in order to do that they use their outer electrons. These electrons are called valence electrons, and they are found in the highest occupied energy level of an atom.

A molecule is the smallest part of a substance. Molecules made up of two atoms are called diatomic. For example, molecular oxygen (O2), nitrogen from the air (N2) and chlorine gas (Cl2).