Question

The oxygen molecule is paramagnetic because:

• A. The bonding electrons outnumber the antibonding electrons in the molecular orbitals
• B. It contains unpaired electrons in the antibonding molecular orbitals
• C. It contains unpaired electrons in the bonding molecular orbitals
• D. The number of bonding electrons equals that of the antibonding electrons in the molecular orbitals

Answer 1

The correct option is B It contains unpaired electrons in the antibonding molecular orbitals

Electronic configuration of $O_2$:
$\left(\sigma 1s^2\right)\left({\sigma }^{\ast }1s^2\right)\left(\sigma 2s^2\right)\left({\sigma }^{\ast }2s^2\right)\left(\sigma 2p_z^2\right)(\pi 2p_x^2=\pi 2p_y^2)({\pi }^{\ast }2p_x^1={\pi }^{\ast }2p_y^1),$

$({\pi }^{\ast }2p_x^1={\pi }^{\ast }2p_y^1)$
Antibonding molecular orbitals, each have one unpaired electron.