Chapter 8, Problem 90A

Interpretation Introduction

Interpretation: The resonance structures for ${\text{HN}}_{\text{3}}$ needs to be drawn.

Concept Introduction: An electron dot structure represents the arrangement of total valence electrons in a molecule. Here, electrons are represented as dots in pairs around the symbol of atoms of the molecule. Resonance structures can be defined as a number of Lewis structures possible for a molecule which explains the delocalization of electrons in the molecule.

Explanation of Solution

According to the question, there are three N atoms bonded in a row and a hydrogen atom is bonded to a nitrogen atom at the end of the row of nitrogen atoms.

The number of valence electrons in the N and H atoms is 5 and 1 respectively. The total number of valence electrons will be:

  $\begin{array}{c}1+3\left(5\right)=1+15\\ =16\end{array}$

Now, the arrangement of electrons around atoms takes place in such a way that there are bonding-pair of electrons and lone-pair of electrons.

The structure can be represented as follows:

  

Here, one nitrogen atom at the terminal position has 2 lone-pair of electrons, the nitrogen atom in the center has no lone pair of electrons, and nitrogen bonded to the hydrogen atom has 1 lone pair of electrons. The delocalization of the lone pair to the double bond is possible in this case and the following resonance structures can be formed: