Q20E - Organic Chemistry (Mcmurry)

Question

Fill in the multiple bonds in the following model of naphthalene, ${\mathbf{C}}_{\mathbf{10}}{\mathbf{H}}_{\mathbf{8}}$ (gray 5 C, ivory 5 H). How many resonance structures does naphthalene have? Draw them.

Step-by-Step Solution

Answer

Naphthalene

There are three resonance structures for naphthalene.

Resonance structures of naphthalene

Step 1: Definition of resonance

Resonance is nothing but the delocalization of electrons within a molecule.

There are certain rules to draw the resonating structure:

1. In a resonating structure, only electrons are move while the position of atoms remains the same.
2. Only pi electrons and lone pair of electrons move.
3. All atoms should be lying on the same plane.

Step 2: Multiple bonds in the naphthalene structure

Naphthalene has a chemical formula ${\mathrm{C}}_{10}{\mathrm{H}}_8$. It contains 19  $\sigma$-bonds and 5 $\pi$-bonds.

Naphthalene

Step 3: Resonance structure of naphthalene

There are a total of three resonance structures for naphthalene. Higher the number of the resonating structure higher will be the stability of that compound. The resonance structure of naphthalene are shown as follow:

Resonance structures of naphthalene