Four diatomic species are listed below in different sequences. Which of these represents the correct order of their increasing bond order?

Question

Aicharya · Accepted Answer

According to molecular orbital theory, the energy level of the given molecules are $\begin{aligned} & \mathrm{C}_2^{2-} ightarrow \sigma 1 s^2 \sigma^{\star} 1 s^2 \sigma 2 s^2 \sigma^{\star} 2 s^2 \pi 2 p_x^2 \pi 2 p_y^2 \sigma 2 p_z^2 \ & 	ext { B.O. }=1 / 2[10-4]=3 \ & \mathrm{He}_2^{+} ightarrow \sigma 1 s^2 \sigma^{\star} 1 s^1 \ & 	ext { B.O. }=1 / 2[2-1]=1 / 2=0.5 \ & \mathrm{NO} ightarrow \sigma 1 s^2 \sigma^{\star} 1 s^2 \sigma 2 s^2 \sigma^{\star} 2 s^2 \sigma 2 p_z^2 \pi 2 p_x^2 \pi 2 p_y^2 \ & \quad \pi^{\star} 2 p_x^1\end{aligned}$ $\begin{aligned} & 	ext { B.O. }=1 / 2[10-5]=2.5 \ & \mathrm{O}_2^{-} ightarrow \sigma 1 s^2 \sigma^{\star} 1 s^2 \sigma 2 s^2 \sigma^{\star} 2 s^2 \sigma 2 p_z^2 \pi 2 p_x^2 \pi 2 p_y^2 \pi^{\star} 2 p_x^2 \ & 	ext { B.O. }=1 / 2[10-7]=1.5 \ & \pi^{\star} 2 p_y^1 \ & \end{aligned}$ So, the correct order of their increasing bond order is $\mathrm{He}_2^{+} < \mathrm{O}_2^{-} < \mathrm{NO} < \mathrm{C}_2^{2-}$

Four diatomic species are listed below in different sequences. Which of these represents the correct order…

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