sp2Hybridorbitalen

Sp2 hybrid orbitals are formed by mixing one s and two p atomic orbitals on the same atom, producing three equivalent sp2 hybrid orbitals. These orbitals are oriented in a trigonal planar arrangement with bond angles of about 120 degrees. The remaining unhybridized p orbital lies perpendicular to the plane and can participate in pi bonding.

Each sp2 orbital has about one third s character and two thirds p character. The sp2 set creates a directional framework for sigma bonds, while the unhybridized p orbital on the same atom remains available for forming pi bonds, enabling multiple bonds and planar structures in many molecules.

In ethene (C2H4), each carbon uses three sp2 hybrids to form sigma bonds to two hydrogens and to the other carbon. The leftover p orbital on each carbon overlaps with the other carbon’s p orbital to form the C=C pi bond, providing the characteristic double bond and planarity of the molecule.

Other common examples include boron trifluoride (BF3), where three sp2 hybrids on boron bond to fluorine atoms in a planar trigonal arrangement. Aromatic and conjugated systems, such as benzene, feature carbon atoms that are effectively sp2-hybridized, allowing delocalized pi bonding over a planar ring.

Limitations and scope: sp2 is a model within valence bond theory that explains geometry and bonding in many molecules but is an approximation. Real molecular geometries can deviate from ideal 120-degree angles, and in some cases molecular orbital theory provides a more accurate description of bonding and delocalization.