Chapter 9, Problem 9.94QE

Interpretation Introduction

Interpretation:

The ion that has longest $\text{N}-\text{O}$ bond and the ion that has shortest $\text{N}-\text{O}$ bond has to be determined.

Concept Introduction:

A covalent bond is a bond that is formed from the mutual sharing of electrons between atoms. Lewis structures are representations of the covalent bond. In this, Lewis symbols show how the valence electrons are present in the molecule.

Steps to write Lewis structures are as follows:

1. The skeleton structure with single bonds between all bonded atoms has to be written

2. Sum the valence electrons of the atoms in the molecule.

(a) For cations, one electron is subtracted for each positive charge.

(b) For anions, one electron is added for each negative charge.

3. Subtract two electrons from total number of valence electrons for each bond in the skeleton structure.

4. Count the number of electrons required to satisfy the octet rule for each atom in the structure. If the number of electrons needed is less than the number remaining, add one bond for every two electrons needed between atoms to attain an octet.

5. The remaining electrons are placed as lone pairs on atoms that need them to satisfy the octet rule.

The formula to calculate formal charge of atom is,

  $\text{Formal}\text{charge}=\left(\begin{array}{l}\text{number}\text{of}\\ \text{valence}\\ \text{electrons}\end{array}\right)-\left(\left(\begin{array}{l}\text{number}\text{of}\\ \text{lone pairs of}\\ \text{electrons}\end{array}\right)+\left(\frac{1}{2}\right)\left(\begin{array}{l}\text{number}\text{of}\\ \text{shared}\\ \text{electrons}\end{array}\right)\right)$        (1)

The bond length is the minimum distance between two bonded atoms in a molecule. The multiple electron pairs have shorter bond lengths. The triple bond has shorter bond length than double bond. Also, the double bond has shorter bond length than single bond.