Bent's rule

Bent's rule states that an atom directs more p character toward electropositive substituents and more s character toward electronegative substituents in its bonding orbitals.

Hybridization: A model that describes atomic bonding orbitals as mixtures of s, p, and sometimes d character. Bent's rule describes how hybrid orbital composition shifts among bonds.
Atomic orbital: A mathematical description of an electron's state and spatial distribution in an atom. Hybrid orbitals are constructed from atomic orbitals.
Fluoromethane: A molecule with one fluorine atom bonded to a carbon atom bearing three hydrogen atoms. Its carbon–fluorine bond illustrates high s-character directed toward an electronegative substituent.
Henry A. Bent: An American chemist known for formulating the rule that bears his name. He introduced the principle linking substituent electronegativity with hybrid-orbital character.
Molecular orbital theory: A theory that describes electrons in molecules using orbitals extending over the molecule as a whole. It explains bonding without requiring Bent's localized hybrid-orbital assignments.
Electronegativity: A measure of an atom's tendency to attract shared electrons in a chemical bond. The relative electronegativities of attached atoms determine the direction of s-character redistribution.
s orbital: An atomic orbital with spherical angular distribution around the nucleus. Its concentration near the nucleus underlies the rule's electronegativity trend.
Chloromethane: A molecule with one chlorine atom bonded to a carbon atom bearing three hydrogen atoms. Comparison with fluoromethane helps reveal substituent-dependent orbital redistribution.
Journal of Chemical Education: A peer-reviewed journal devoted to research and practice in chemistry education. Bent presented the rule in a 1961 article in this journal.
Trigonal planar molecular geometry: A geometry in which three atoms lie in one plane around a central atom at roughly 120-degree angles. Idealized geometry alone does not capture substituent-driven s-character redistribution.

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