The molecule shown here is styrene, C8H8, a benzene derivative that is used to make a number of polymers, including polystyrene. The shorthand notation for the benzene ring (described in Section 8.6) is used. Three of the carbon–carbon bonds are numbered in the structure.
a. Which of the three bonds is the strongest?
b. Which of the three bonds is the longest?
c. Which of the three bonds is best described as halfway between a single and a double bond? [Sections 8.6 and 8.8]

Key Concepts

Bond Strength

Bond strength refers to the energy required to break a bond between two atoms. In organic molecules, bonds can vary in strength based on their type; for example, double bonds are generally stronger than single bonds due to the presence of two shared electron pairs. Understanding bond strength is crucial for determining which bond in styrene is the strongest.

Bond Length

Bond length is the distance between the nuclei of two bonded atoms. Typically, single bonds are longer than double bonds because the additional electron pair in a double bond pulls the atoms closer together. Analyzing the bond lengths in styrene helps identify which bond is the longest among the three specified.

Resonance

Resonance is a concept in chemistry that describes the delocalization of electrons in molecules where bonds can be represented by multiple structures. In styrene, the carbon-carbon bond that is halfway between a single and a double bond is indicative of resonance, where the bond characteristics are averaged due to the presence of alternating single and double bonds in the benzene ring.