Chapter 8.3, Problem 43PP

Interpretation Introduction

Interpretation:

The Lewis structure of ${\text{NO}}_{\text{2}}^{-}$ is to be drawn.

Concept introduction:

The strategy for drawing the Lewis structure is mentioned below:

• Calculate the number of valence electrons present in the molecule.
• Calculate the electron pairs by diving the number of valence electrons by 2.
• Determine the bond pairs.
• Determine the lone pairs.
• Check whether the central atom satisfies the octet rule.

Answer to Problem 43PP

The Lewis structure of ${\text{NO}}_{\text{2}}^{-}$ is drawn below.

Explanation of Solution

The number of the valence electron in ${\text{NO}}_{\text{2}}^{-}$ is the sum of the valence electron in nitrogen, two oxygen atoms, and one electron (negative charge). The valence electron in nitrogen is five and the valence electron in oxygen is six. Therefore, the valence electron in ${\text{NO}}_{\text{2}}^{-}$ is calculated as shown below.

$\begin{array}{c}\text{No}\text{.}\text{of}\text{valence}\text{electron}=\text{N}+\text{2O}+1{\text{e}}^{-}\\ =5{\text{e}}^{-}+2\times 6{\text{e}}^{-}+1{\text{e}}^{-}\\ =18{\text{e}}^{-}\end{array}$

The number of electron pairs is calculated as shown below.

$\begin{array}{c}\text{electron}\text{pair}=\frac{18{\text{e}}^{-}}{2}\\ =9{\text{e}}^{-}\text{pairs}\end{array}$

Among nine electron pairs, three electron pairs are involved in bonding and the six electron pairs remain as lone pairs. The Lewis structure of ${\text{NO}}_{\text{2}}^{-}$ is drawn below.

Conclusion

The Lewis structure of ${\text{NO}}_{\text{2}}^{-}$ is drawn as follows: