3.4.3—Terms

Bond energy is the energy required to break one mole of a particular covalent bond in the gaseous state, measured in kJ mol⁻¹. Bond length is the internuclear distance between two covalently bonded atoms.

Greater attraction between bonding electrons and nuclei pulls atoms closer, giving a shorter bond length and a stronger bond. Greater bond energy therefore indicates a stronger covalent bond.

Bond multiplicity changes electron density between nuclei: triple bonds are generally shortest and strongest, double bonds intermediate, and single bonds longest and weakest. Use supplied values and units when comparing bonds.

Use bond polarity, bond strength and bond type (σ/π) as the source-supported factors when comparing covalent-molecule reactivity. A longer, weaker bond may require less energy to break, but do not treat one factor as a universal complete reactivity prediction.