Valence Bond Theory
The bonding model in which a covalent bond forms by the overlap of half-filled atomic orbitals on adjacent atoms.
Unit
Dimensionless
In depth
Developed by Heitler, London and Pauling, it keeps electrons localised between specific atom pairs and introduces hybridisation to account for observed geometries. It gives an intuitive picture of directed bonds but cannot explain the paramagnetism of O₂ or the spectra of coloured complexes without invoking resonance.
Examples in the real world
Overlapping two hydrogen 1s orbitals to make H₂; overlapping sp³ hybrids with 1s orbitals to make methane.