Question

Which of the following structures does not exhibit resonance?
a.) ${{O}_{3\,}}$
b.) $S{{O}_{3}}$
c.) $N{{O}_{3}}^{-}$
d.) $N{{H}_{4}}^{+}$

Answer 1

Hint: Resonance is described as the phenomenon as a result of which a molecule can be expressed in different forms, none of them can explain all the properties of the molecules. The actual structure of the molecule is called resonance hybrid.

Complete step by step solution:

Ozone (${{O}_{3\,}}$) consists of a central oxygen atom, which is singly bonded to one oxygen of the atom and doubly bonded to another. There is no net charge on this molecule, but when we draw the Lewis structures of this molecule it shows a +1 charge on the central oxygen and a -1 charge on the singly bonded oxygen. Therefore, Ozone has two major structures of resonance that contribute equally to the molecule's overall hybrid structure.
Sulphur trioxide ($S{{O}_{3}}$) contains Sulphur as a central atom with three Oxygen attached to it. So, when we draw the Lewis structure, three structures will have Sulphur (S) with a formal charge of +2 and two of the structures will have O atoms with a formal charge of -1. Now, in the next three structures, S will have a formal charge of +1 and one of the O atoms has a formal charge of -1. Now in the last structure all atoms have a formal charge of zero i.e. Sulphur is doubly bonded to all the oxygen atoms. So, there are seven resonance structures for $S{{O}_{3}}$.
Nitrogen is the central atom in a nitrate ion ($N{{O}_{3}}^{-}$). It is singly bonded to the two oxygen atoms and doubly bonded to one oxygen atom. The oxygen atoms that are singly bonded to the nitrogen hold a charge of -1. The central atom has a charge of +1 and the overall charge on the nitrate ion is -1. The three possible resonance structures $N{{O}_{3}}^{-}$, $N{{H}_{4}}^{+}$ don’t have any Lewis structure as when we draw the Lewis structure of Ammonium ion , it forms a single bond with each of the hydrogen atoms and there is no double bond formation.

Therefore, the correct answer is (d).

Note: Resonance is a way to describe the combination of several contributing structures into a hybrid resonance (or hybrid structure) in valence bond theory in certain molecules or ions. It is a hypothetical phenomenon; it is impossible to say whether or not any given individual molecule with a resonance structure is literally in one configuration or another.