Question

Which molecule/ion out of the following does not contain unpaired electrons?

• A. $N_{2}^{+}$
• B. $O_{2}$
• C. $O_{2}^{2 -}$
• D. $B_{2}$

Answer 1

Answer: (C)

$O_{2}^{2 -}$

Answer 2

: $N_{2}^{+}(13) = \sigma 1s^{2},\sigma*1s^{2},\sigma 2s^{2},\pi 2p_{x}^{2} = \pi 2P_{y}^{2}\sigma 2P_{z}^{1}$

$O_{2}(16) = \sigma 15s^{2},\sigma*1s^{2},\sigma 2s^{2},\sigma*2s^{2},\sigma 2p_{z}^{2}$

$\pi 2p_{x}^{2} = \pi 2p_{y}^{2},\pi*2p_{x}^{1} = \pi*2P_{y}^{1}$

$O_{2}^{2 -}(18) = \sigma 1s^{2},\sigma*1s^{2},\sigma 2s^{2},\sigma*2s^{2},\sigma 2p_{z}^{2},\pi 2p_{x}^{2}$

$= \pi 2p_{y}^{2},\pi*2p_{x}^{2} = \pi*2P_{y}^{2}$

$B_{2}(10) = \sigma 1s^{2},\sigma*1s^{2},\sigma 2s^{2},\sigma*2s^{2},\pi 2p_{x}^{1} = \pi 2p_{y}^{1}$

Thus, $O_{2}^{2 -}$does not contain unpaired electrons.