Question

What is meant by the term bond order? Calculate the bond order of: N₂, O₂, O₂⁺ and O₂^-.

Answer 1

Bond order is defined as one half of the difference between the number of electrons present in the bonding and anti-bonding orbitals of a molecule.

Bond order = 1/2(N_b - N_a)

Bond order of N₂ 

Number of bonding electrons, N_b = 10 

Number of anti-bonding electrons, N_a = 4

Bond order of nitrogen molecule = 1/2(10 - 4) = 3

Bond order of O₂ 

Bond order = 1/2(N_b - N_a) = 1/2(8 - 4) = 2

Hence, the bond order of oxygen molecule is 2. 

Similarly, the electronic configuration of O⁺ can be written as:

Bond order of O₂⁺ = 1/2(8 - 3) = 2.5

The electronic configuration of O₂⁺ ion will be :

Bond order of O₂^- = 1/2(8 - 5) = 1.5