Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?
A molecule of hydrogen is formed by the combination of two atoms of hydrogen with one electron each present in the 1s orbital. hydrogen (1s1) has one electron less than the stable inert gas configuration (He;1s2) and therefore it shares its single electron with an electron of another hydrogen atom to form a stable diatomic molecule. Thus two electrons are present in the hydrogen molecule and both will be accommodated in the molecular orbital of lowest energy. The bond order of H2 is +1. The positive value of bond order indicates that the H2 (diatomic) molecules are stable.