Question

Question: Draw as many resonance structures as you can for the following

species:

Short answer

Answer

These are three resonance forms.

Step-by-step solution

Resonance

Resonance is a method to represent delocalized electrons within certain molecules or polyatomic ions when the bonding cannot be concluded by a single Lewis structure.

Resonance occurs when two double bonds are present consecutively, or a double bond is followed by a single bond which is followed by another double bond, triple bond, positive charge, negative charge, or a free radical.

Rules for structures of resonance form

Rule 1

Individual resonance forms are imaginary; they are not real. The real structure is a composite or resonance hybrid of all the forms.

Rule 2

Resonance forms differ only in the placement of their or nonbonding electrons. So, the position or the hybridization of an atom doesn’t change.

Rule 3

Different resonance forms of molecules don’t have to be equivalent. It can be converted into its anion by reaction with a strong base. The resultant anion can have resonance forms.

Rule 4

Resonance forms obey normal rules of valency. A resonance form, like any other structure, has to follow the octet rule.

Rule 5

The resonance hybrid is more stable than any individual resonance form. So, resonance leads to stability. The more the number of resonance structures, the more stability will be.

Structures of resonance forms

We will see if the rules are followed:

Here all rules are followed:

Rule 2: Resonance forms differ only in the placement of their or nonbonding electrons. So, the position or the hybridization of an atom doesn’t change.

Here, the position of only ornonbonding electron is changed.

Rule 4: Resonance forms obey normal rules of valency. Like any other structure, a resonance form has to follow the octet rule.

Here, each atom follows the octet rule.

So, it can be concluded these are three resonating forms possible.