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

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

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

On solving n = 1

Unpaired electron (n) $=1$

$O_2^{+}=\sigma 1s^2,\sigma \ast 1s^2,\sigma 2s^2,\sigma \ast 2s^2,\sigma 2p_2^2,\pi 2p_x^2=\pi 2p_y^2,\pi \ast 2p_x^1=\pi \ast 2p_y$

$O_2^{-}=\sigma 1s^2,\sigma \ast 1s^2,\sigma 2s^2,\sigma \ast 2s^2,\sigma 2p_2^2,\pi 2p_x^2=\pi 2p_y^2,\pi \ast 2p_x^2=\pi \ast 2p_y^1$

Hence $O_2^{-}$ and $O_2^{+}$ have one unpaired electron.