sp2hybridized

Sp2hybridized refers to the state of an atom in which one s orbital mixes with two p orbitals to form three degenerate sp2 hybrid orbitals. The remaining unhybridized p orbital, perpendicular to the plane of the sp2 hybrids, can participate in pi bonding. This arrangement arises in valence bond theory when the central atom has three electron domains surrounding it.

The three sp2 orbitals point toward the corners of a trigonal arrangement, giving bond angles of about 120 degrees in the molecular plane. As a result, the geometry around the atom is typically planar, though real structures may deviate slightly due to substituents or lone pairs.

Bond formation involves sigma and pi components. The sp2 orbitals form sigma bonds to neighboring atoms or contain lone pairs, while the unhybridized p orbital overlaps with another p orbital to form a pi bond. In ethene (C2H4), each carbon is sp2 hybridized, enabling a C=C double bond composed of one sigma bond (sp2–sp2 overlap) and one pi bond (p–p overlap). In boron trifluoride (BF3), boron is sp2-hybridized with three sigma bonds to fluorine and an empty p orbital.

In aromatic systems, such as benzene, all ring carbons are sp2-hybridized, supporting a continuous delocalized pi network over the ring. Hybridization is a modeling concept within valence bond theory; some molecules exhibit resonance or MO descriptions that describe electron distribution beyond a single sp2 picture.