Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?

Hydrogen cannot exists as monoatomic molecule because in monoatomic state hydrogen atom is unstable. Hydrogen atom contains only one electron and to achieve the stable noble gas configuration as that of Helium two hydrogen atoms share one electron with each other to form a diatomic molecule and hence hydrogen exists as a diatomic molecule in Free State or under normal conditions.