Question

Indigo is the dye used in coloring blue jeans. The term navy blue is derived from the use of indigo to dye British naval uniforms in the eighteenth century. The structure of the indigo molecule is

a. How many sigma bonds and pi bonds exist in the molecule?

b. What hybrid orbitals are used by the carbon atoms in the indigo molecule?

Short answer

1. There are $33\sigma$bonds and $9\pi$bonds exist in the molecules.
2. Carbon atom use $s{p}^2$hybrid orbitals.

Step-by-step solution

Calculating the number of sigma and pi bonds.

From the structure of the indigo molecule, there are $33\sigma$bonds and $9\pi$bonds in the given molecules. Every single bond contains one $\sigma$bond and every double bond contains one $\pi$bond and one $\sigma$bond.

Hybridization of the C atoms.

All the carbon atoms in the indigo molecules are ${\text{sp}}^{\text{2}}$hybridized as all the carbon atoms have double bonds.