Hybridisierung

Hybridisierung, in English often rendered as hybridization, is a concept in chemistry describing how atomic orbitals on an atom mix to form new, equivalent orbitals that participate in bonding. The resulting hybrid orbitals have defined directional character, allowing the prediction of molecular geometries via VSEP theory. The type of hybridization depends on the number and arrangement of electron pairs around the central atom: sp (two orbitals, linear), sp2 (three orbitals, trigonal planar), sp3 (four orbitals, tetrahedral). Heavier-element cases use sp3d or sp3d2 to describe trigonal bipyramidal and octahedral geometries, respectively; sometimes dsp3 is also cited. Each hybrid orbital is a linear combination of the atom’s atomic orbitals (s, p, and occasionally d).

Examples: In methane, carbon forms four sigma bonds using sp3 hybrids, giving an approximately tetrahedral shape with bond angles close to 109.5°. In ethene, each carbon uses sp2 hybrids for sigma bonds, with the remaining unhybridized p orbital forming the pi bond; the molecule is planar with ~120° angles. In acetylene, sp hybrids provide two sigma bonds per carbon and two pi bonds, giving a linear molecule. In sulfur hexafluoride, sp3d2 hybrids describe six bonding pairs.

Relation to other theories: Hybridization is a convenient description within valence bond theory and is often reconciled with molecular orbital theory. It is a useful teaching tool but not a unique physical observable; real molecular orbitals are delocalized. History: Introduced by Linus Pauling in the 1930s to rationalize shapes and bonding.