Chapter 9.3, Problem 1RC

What is the N—O bond order in nitrogen monoxide, NO?

1. (a) 2
2. (b) 2.5
3. (c) 3.0
4. (d) 1

Interpretation Introduction

Interpretation:

The nitrogen monoxide ( $NO$) molecule bond order should be calculate and identified.

Concept Introduction:

Molecular orbital (MO) theory:  is a method for determining molecular structure in which electrons are not assigned to individual bonds between atoms, but are treated as moving under the influence of the nuclei in the whole molecule.

Bond order: The bond order has defined as the net number of bonding electrons pairs linking a pair of atoms. This same concept can be applied directly to molecular orbital theory, but not bond order is defined as.

$\text{Bond}\text{order}\text{=}\frac{\text{1}}{\text{2}}\left(\begin{array}{l}\text{Number}\text{of}\text{electrons}\text{in}\text{bondoing}\text{MOs-}\\ \text{Number}\text{of}\text{electrons}\text{in}\text{antibonding}\text{MOs}\end{array}\right)$

Answer to Problem 1RC

The nitrogen monoxide (NO) molecule bond order has 2.5, and option (b) is correct one.

To determine:  The nitrogen monoxide (NO) molecule bond order should be identified.

Explanation of Solution

Molecular orbital correlation diagram of (NO) molecule

$\begin{array}{l}{\text{σ*}}_{\text{2p}}{}_{{}_{\text{z}}}\\ --\boxed{}--\to (\text{Anti}\text{bonding}\text{electrons})\\ \\ --\boxed{\uparrow }-\boxed{}--\\ {\text{π*}}_{\text{2p}}{\text{π*}}_{\text{2p}}\\ \\ --\boxed{}-\boxed{}-\boxed{}----\boxed{}-\boxed{}-\boxed{}--\\ {\text{2}}_{\text{px}}{\text{2}}_{\text{py}}{\text{2}}_{\text{pz}}{\text{2}}_{\text{px}}{\text{2}}_{\text{py}}{\text{2}}_{\text{pz}}\\ \\ \\ --\boxed{\uparrow \downarrow }-\boxed{\uparrow \downarrow }--\\ {\text{π}}_{\text{2px}}{\text{π}}_{\text{2py}}\\ {\text{σ}}_{\text{2pz}}\\ --\boxed{\uparrow \downarrow }--\to (\text{Bonding}\text{electrons})\\ \end{array}$

          $\begin{array}{l}\\ --\boxed{\uparrow \downarrow }--\to (\text{Anti}\text{bonding}\text{electrons})\\ \left(\sigma *2s\right)\\ \\ --\boxed{\uparrow \downarrow }----\boxed{\uparrow \downarrow }--\\ 2s2s\\ \\ --\boxed{\uparrow \downarrow }--\to (\text{Bonding}\text{electrons})\\ {\left(\sigma 2s\right)}^2\end{array}$

Calculation method of bond order of (NO) molecule

$\begin{array}{l}\text{Bond}\text{order}\text{=}\frac{\text{1}}{\text{2}}\left(\begin{array}{l}\text{Number}\text{of}\text{electrons}\text{in}\text{bondoing}\text{MOs-}\\ \text{Number}\text{of}\text{electrons}\text{in}\text{antibonding}\text{MOs}\end{array}\right)\\ \text{Bond}\text{order}\text{=}\frac{(8-3)}{\text{2}}=\frac{5}{\text{2}}=2.5\end{array}$

Conclusion

The nitrogen monoxide (NO) molecule bond order was calculated.