Order these compounds in order of decreasing carbon–carbon bond length: HCCH, H₂CCH₂, H₃CCH₃.

Key Concepts

Bond Length

Bond length is the distance between the nuclei of two bonded atoms. In general, bond lengths vary depending on the type of bond (single, double, or triple) and the atoms involved. Shorter bonds typically indicate stronger interactions, while longer bonds suggest weaker interactions. Understanding bond length is crucial for comparing the structural characteristics of different compounds.

Types of Carbon Bonds

Carbon can form single, double, or triple bonds with other carbon atoms. Single bonds (as in alkanes) are the longest and weakest, while triple bonds (as in alkynes) are the shortest and strongest. The type of bond significantly influences the physical properties of the compound, including bond length. Recognizing these differences is essential for ordering compounds based on their carbon–carbon bond lengths.

Hybridization

Hybridization is the concept of mixing atomic orbitals to form new hybrid orbitals that can accommodate bonding. In carbon compounds, sp, sp², and sp³ hybridizations correspond to triple, double, and single bonds, respectively. The hybridization state affects the geometry and bond lengths of the molecules. Understanding hybridization helps predict the bond lengths in the given compounds.