Question

Find the bond order of peroxide ion.

Answer 1

Peroxide ion is $O_2^{2-}$ and it has $18$ electrons.
$(\sigma 1s{)}^2,({\sigma }^{\ast }1s{)}^2,(\sigma 2s{)}^2,({\sigma }^{\ast }2s{)}^2,(2p_z{)}^2,(\pi {)}^4,({\pi }^{\ast }{)}^4$
So Bond Order $=\frac{1}{2}(a-b)$.
a is the number of electrons in bonding molecular orbitals and
b is the number of electrons in antibondng molecular orbitals.
Bond Order $=\frac{1}{2}(10-8)$$=1$.