5.1 Theory of hybrid orbital and atomic orbital hybridization 1.Hybrid orbital theory---Proposed by Pauling in 1928 Chemical bonding theories MOLECULAR ORBITAL THEORY Valence electrons are delocalized Valence electrons spread over entire molecule VALENCE BOND THEORY Valence electrons are localized between atoms (or are lone pairs). Half-filled atomic orbitals overlap to form bonds.MOLECULAR ORBITAL THEORY • Valence electrons are delocalized • Valence electrons spread over entire molecule. Chemical bonding theories VALENCE BOND THEORY • Valence electrons are localized between atoms (or are lone pairs). • Half-filled atomic orbitals overlap to form bonds. §5.1 Theory of hybrid orbital and atomic orbital hybridization 1. Hybrid orbital theory ---Proposed by Pauling in 1928