Question

Number of unpaired electrons in ${{O}_{2}}$ molecule is:

• A. zero
• B. one
• C. two
• D. four

Answer 1

Answer: (C)

The molecular orbital elctronic configuration of ${{O}_{2}}$ is -
${{O}_{2}}(16{{e}^{-}})=\sigma 1{{s}^{2}}{{\sigma }^{*}}1{{s}^{2}}\sigma 2{{s}^{2}}{{\sigma }^{*}}2{{s}^{2}}\sigma 2p{{x}^{2}}$ $\pi 2p{{y}^{2}}\pi 2p{{z}^{2}}{{\pi }^{*}}2p{{y}^{1}}{{\pi }^{*}}2p{{z}^{1}}$ Hence, it has two unpaired Iectrons and B paramagnetic.