Orbitalentheorie

Orbitalentheorie, also known as Valence Bond Theory, is a chemical theory that describes the covalent bond as the overlap of atomic orbitals. It posits that a chemical bond is formed when an atomic orbital from one atom overlaps with an atomic orbital from another atom, and this overlap results in the sharing of electrons between the two atoms. The strength of the bond is related to the degree of overlap.

This theory helps explain the directional nature of covalent bonds. For example, the formation of a sigma bond involves the head-on overlap of atomic orbitals, leading to a strong bond with electron density concentrated along the internuclear axis. Pi bonds, on the other hand, are formed by the sideways overlap of atomic orbitals, resulting in electron density above and below the internuclear axis.

Orbitalentheorie also accounts for molecular geometry through the concept of hybridization. Hybridization involves the mixing of atomic orbitals to form new hybrid orbitals that are more suitable for bonding and explain the observed shapes of molecules. For instance, in methane, the carbon atom's s and p orbitals hybridize to form four sp3 hybrid orbitals, which are arranged tetrahedrally and form sigma bonds with hydrogen atoms.

While Orbitalentheorie provides a good qualitative description of bonding, it has limitations, particularly in explaining phenomena like paramagnetism in molecules like oxygen, which is better described by Molecular Orbital Theory. Nevertheless, it remains a fundamental and widely used concept in understanding chemical bonding.