Mothballs are composed of naphthalene, C₁₀H₈, a molecule that consists of two six-membered rings of carbon fused along an edge, as shown in this incomplete Lewis structure:
(b) Do you expect the C—C bond lengths in the molecule to be similar to those of C—C single bonds, C ═ C double bonds, or intermediate between C—C single and C ═ C double bonds?

Key Concepts

Bond Lengths and Types

In chemistry, bond lengths vary depending on the type of bond between atoms. C—C single bonds are longer than C═C double bonds due to the increased electron density and stronger attraction in double bonds, which pulls the atoms closer together. Understanding these differences is crucial for predicting molecular structure and behavior.

Resonance Structures

Molecules like naphthalene can exhibit resonance, where multiple valid Lewis structures can represent the same molecule. This delocalization of electrons can lead to bond lengths that are intermediate between single and double bonds, as the electrons are not localized to a single bond but are spread over multiple bonds.

Molecular Geometry and Hybridization

The geometry of a molecule and the hybridization of its atomic orbitals influence bond lengths and angles. In naphthalene, the carbon atoms are sp² hybridized, which affects the bond character and lengths. Understanding hybridization helps in predicting the molecular shape and the nature of the bonds present.