Ncert Exercises & Solutions

Write Lewis structure of the following compounds and show formal charge on each atom.

${HNO}_{3}, {NO}_{2}, H_{2} {SO}_{4}$

The Lewis structure of the following compounds and formal charge on each atom are as

(i) HNO₃

Formal charge on an atom in a Lewis structure=[total number of valence electrons in free atom]-[total number of non-bonding (lone pairs) electrons]-

\frac{1}{2}

[total number of bonding or shared electrons]

Formal charge on H

= 1 - 0 - \frac{1}{2} \times 2 = 0

Formal charge on N

= 5 - 0 - \frac{1}{2} \times 8 = 1

Formal charge on O(1)

= 6 - 4 - \frac{1}{2} \times 4 = 0

Formal charge on O(2)

= 6 - 4 - \frac{1}{2} \times 4 = 0

Formal charge on O(3)

= 6 - 6 - \frac{1}{2} \times 2 = - 1

(ii) NO₂

Formal charge on O(1)

= 6 - 4 - \frac{1}{2} \times 4 = 0

Formal charge on N

= 5 - 1 - \frac{1}{2} \times 6 = + 1

Formal charge on O(2)

= 6 - 6 - \frac{1}{2} \times 2 = - 1

(iii) H₂SO₄

Formal charge on H(1) or H(2)

= 1 - 0 - \frac{1}{2} \times 2 = 0

Formal charge on O(1) or O(3)

= 6 - 4 - \frac{1}{2} \times 4 = 0

Formal charge on O(2) or O(4)

= 6 - 6 - \frac{1}{2} \times 2 = - 1

Formal charge on S

= 6 - 0 - \frac{1}{2} \times 8 = + 2