sphybridisering

Sp-hybridization, sometimes written sp-hybridisering in some languages and often referred to as sp hybridization, is a concept in valence bond theory describing how atomic orbitals mix to form new, equivalent orbitals. It involves the mixing of one s orbital and one p orbital on a central atom to produce two degenerate sp hybrid orbitals that are arranged 180 degrees apart, leading to linear geometry for the electron domains involved.

This hybridization occurs when the central atom has two electron domains around it (such as two sigma bonds or one sigma bond and one lone pair). The two sp hybrids form the sigma framework of the molecule, while the remaining unhybridized p orbitals (one on each participating atom) participate in pi bonding, enabling multiple bonds. This combination explains molecules with linear or near-linear structures.

Common examples include carbon in carbon dioxide (CO2), beryllium chloride (BeCl2) in the gas phase, and acetylene (C2H2). In CO2, carbon uses two sp hybrids to form two sigma bonds with oxygens, with two pi bonds formed by unhybridized p orbitals, yielding a linear molecule. In acetylene, each carbon uses sp hybrids to form sigma bonds with the other carbon and with a hydrogen atom, while the triple bond arises from two pi bonds.

Sp-hybridization is a modeling concept within valence bond theory. In more advanced treatments, molecular orbital theory provides a more general description of bonding, but sp hybridization remains a useful approximation for predicting geometry and bonding in appropriate cases.