Topic overview

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In VB theory, a covalent bond forms when suitable atomic orbitals overlap and their electrons pair in the overlap region. Bond strength is greatest at an optimum internuclear distance, where potential energy is minimized, and generally increases with the extent of orbital overlap. Head-on overlap forms σ bonds, while side-on overlap forms π bonds. Hybridization combines orbitals on the same atom to support directional bonding and help account for common geometries and bond angles. VB theory also describes localized bonding and lone pairs, while resonance represents delocalized electron character through a hybrid of contributing structures. The lesson introduces VB wavefunction construction, bond order, and the theory’s limitations, including cases better explained by molecular orbital theory.