Question

Which of the folowing compounds have a non-integral bond order?

• A. $O_2^{+}$
• B. $O_2^{-}$
• C. $NO$
• D. All of these

Answer 1

The correct option is D All of these

MOs for:
$O_2^{+}:\sigma 1s^2{\sigma }^{\ast }1s^2\sigma 2s^2{\sigma }^{\ast }2s^2\sigma 2p_z^2\left(\pi 2p_x^2\pi 2p_y^2\right){\pi }^{\ast }2p_x^1$

$O_2^{-}:\sigma 1s^2{\sigma }^{\ast }1s^2\sigma 2s^2{\sigma }^{\ast }2s^2\sigma 2p_z^2\left(\pi 2p_x^2\pi 2p_y^2\right)\left({\pi }^{\ast }2p_x^2{\pi }^{\ast }2p_y^1\right)$

$NO:\sigma 1s^2{\sigma }^{\ast }1s^2\sigma 2s^2{\sigma }^{\ast }2s^2\sigma 2p_z^2\left(\pi 2p_x^2\pi 2p_y^2\right){\pi }^{\ast }2p_x^1$
Since bond order in MOT is given by,
$BO=\frac{\text{Bonding electrons - antibonding electrons}}{2}$
Therefore,
$O_2^{+}\to 2.5$
$O_2^{-}\to 1.5$
$NO\to 2.5$