The paramagnetism of O₂ is explained by MO theory because the molecule has:
- sp² hybridisation
- Two unpaired electrons in π*2p_x and π*2p_y MOs
- Two lone pairs on each oxygen
- A triple bond
Show answer and solution
Correct answer: B. Two unpaired electrons in π*2p_x and π*2p_y MOs
O₂ MO configuration: KK(σ2s)²(σ*2s)²(σ2p_z)²(π2p_x)²(π2p_y)²(π*2p_x)¹(π*2p_y)¹.
The two π* orbitals are each singly occupied
→ **two unpaired electrons**
→ paramagnetic — a triumph of MO theory over Lewis.