Discuss the bonding in oxygen `(O_2)` molecule by molecular orbital theory.

Explanation

According to molecular orbital theory, the electronic configuration of `O_2` molecule is,
`O_(2), sigma1s^(2), sigma^(**)1s^(2), sigma2s^(2), sigma^(**)2s^(2), sigma2p_(z)^(2), (pi2p_(x)^(2)= pi2p_(y)^(2)), (pi^(**)2p_(x)^(1)= pi^(**)2p_(y)^(1))`
In `O_2` molecule, ten electrons are present in bonding molecular orbitals ans six electrons are present in anitibonding molecular orbitals. Its bond order is : Bond order `=[N_(b)-N_(a)] =(1)/(2)[10-6]= 2`
The atoms are held by double bond. It contains two unpaired eletrons in `pi^(**)2p_(x)` and `pi^(**)2p_(y)` molecular orbitals. Therefore, `O_2` molecule is paramagnetic in nature.