Question

Which ofthe diatomic molecular species has only π bonds according to Molecular Orbital Theory ?
(1) O₂
(2) N₂
(3) C₂
(4) Be₂

Answer 1

$C_2$ has only $\pi$ bonds according to MOT

Explanation:

Molecular orbital theory explains that the molecules are formed by the combination of atoms and molecular orbitals are formed by the combination of atomic orbitals of combining atoms.

• In given species, Oxygen has valency molecular orbitals as $\pi 2p_y^2=\pi 2p_z^2, \sigma 2p_x^2, \pi^* 2p_y^1=\pi^* 2p_z^1$

• Nitrogen has valency molecular orbitals as $\pi 2p_y^2=\pi 2p_z^2, \sigma 2p_x^2$                          

• Carbon has valency molecular orbitals as $\pi 2p_y^2=\pi 2p_z^2$        

• Berylium has valency molecular orbitals as $\sigma 2s^2, \sigma^* 2s^2$          
• From above configurations it can be observed that Carbon has only $\pi$ bonds according to Molecular orbital theory