Question

Resonance is not observed in:
A. $C{O_2}$
B. $N{H_3}$
C. $S{O_3}$
D. $N{O_2}$

Answer 1

We know that resonance by definition is “when all physical and chemical properties of the compound are not explained by a single structure, but different structures are required to explain the property then these structures are called resonating forms and the phenomena is called resonance.

Complete step by step solution:
For a compound to show resonating structure, it should have a planar structure, follow Huckel’s rule of electron number, hybridization remains same and fixed, and number of lone pairs remain same. When a compound has lone pairs of electron and double bond on the next atom, then that compound will show a resonating structure. $C{O_2}$,$S{O_3}$,$N{O_2}$ all the compounds have double bonds so they show resonating structure. But an ammonia molecule has no double bond so it has no resonating structure.

Therefore, resonating structure is not observed in $N{H_3}$.

Note:
Through the resonating structure we can decide the stability of the compound., resonating structure with complete octet of every atom is more stable than the resonating structure in which incomplete octet of any atoms are present. We know that a neutral resonating structure is more stable than the polar resonating structure. In between two polar resonating structures, the canonical structure in which negative charge is on more electronegative atoms and positive charge is on less electronegative atoms, is more stable.