The energies of molecular orbitals in diatomic molecules

In order to be sure that a bond actually forms between two atoms linked by a molecular orbital it is necessary to calculate the energies of the molecular orbitals and then allocate electrons to them. In essence, the approximate Schrodinger equation 

When two helium atoms interact there are four electrons to place in the orbitals and so both the t1s and the 7 Is orbitals will be filled. The effect of the filled antibonding orbital completely negates the effect of the filled bonding orbital. No energy is gained by the system and so He2 does not form. 

Molecule Ground-State configuration Bond length/ nm Bond energy/ kJ mor  

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