Question

If the magnetic moment of a dioxygen species is 1.73 B.M, it may be

• A. $O_{2}$ or $O_{2}^{-}$
• B. $O_{2},O_{2}^{-}$ or $O_{2}^{-}$
• C. $O_{2},O_{2}^{+}$
• D. $O_{2}^{-}$ or $O_{2}^{+}$

Answer 1

Answer: (D)

Magnetic moment $=1.73$ BM

$\mu =\sqrt{n \left(\right. n + 2 \left.\right)}$

$1.73=\sqrt{n \left(\right. n + 2 \left.\right)}$

On solving n = 1

Unpaired electron (n) $=1$

$O_{2}^{+}=\sigma 1s^{2},\sigma *1s^{2},\sigma 2s^{2},\sigma *2s^{2},\sigma 2p_{2}^{2},\pi 2p_{x}^{2}=\pi 2p_{y}^{2},\pi *2p_{x}^{1}=\pi *2p_{y}$

$O_{2}^{-}=\sigma 1s^{2},\sigma *1s^{2},\sigma 2s^{2},\sigma *2s^{2},\sigma 2p_{2}^{2},\pi 2p_{x}^{2}=\pi 2p_{y}^{2},\pi *2p_{x}^{2}=\pi *2p_{y}^{1}$

Hence $O_{2}^{-}$ and $O_{2}^{+}$ have one unpaired electron.