When the atoms combining to form molecules are of the same type, it is a homoatomic molecule. For example, when two Hydrogen atoms (2H) combine under an appropriate reaction condition, a Hydrogen molecule (H2) is formed.
A homoatomic molecule can be diatomic (like elemental hydrogen, H2), triatomic (like ozone, O3), or polyatomic (like sulphur allotrope, S8).
In simpler terms, these homoatomic molecules are made of identical types of atoms. Therefore, at times, they may also be referred to as homonuclear molecules.
