Question

The bond order and magnetic behaviour of $O_2^{-}$ion are, respectively:

• A. 1.5 and paramagnetic
• B. 1.5 and diamagnetic
• C. 2 and diamagnetic
• D. 1 and paramagnetic

Answer 1

Answer: (A)

$O_2^{-}={\left({\sigma }_{1s}\right)}^2{\left({\sigma }_{1s}^{\ast }\right)}^2{\left({\sigma }_{2s}\right)}^2{\left({\sigma }_{2s}^{\ast }\right)}^2{\left({\sigma }_{2p_z}\right)}^2$
$\left({\pi }_{2p_x}^2={\pi }_{2p_y}^2\right)\left({\pi }_{2p_s}^{\ast 2}={\pi }_{2py}^{\ast 1}\right)$
Bond order $=\frac{10-7}{2}=1.5$
and paramagnetic