Question

The valence MO theory sequence for Li2 is: σ(2s) < σ*(2s) < σ(2p) < π(2p)=π(2p) < π*(2p)=π*(2p) < σ*(2p)
What is the bond order of Li₂¹⁺?

Answer 1

Bond order = [Number of electrons in bonding orbitals - Number of electrons in antibonding orbitals] / 2

• The orbitals having esterik sign (*) represent the antibonding orbitals.
• The orbitals having no estrik sign represent the bonding orbitals.

Li₂⁺ has 5 electrons which have to be filled in the orbitals as follows:

σ(2s)² < σ*(2s)² < σ(2p)¹ < π(2p)=π(2p) < π*(2p)=π*(2p) < σ*(2p)

We can see that total electrons in bonding orbitals = 3 and electrons in the antibonding orbitals = 2

Hence, Bond order = 3 - 2 / 2 = 1/2 = 0.5