ABSTRACT
Each central atom in a molecule can be described by its bond types, hybridization, geometries, and resulting polarity. A sigma bond is an end-to-end overlap of orbitals, which provides a spherically symmetrical electron-density distribution around the bond axis; it allows bonded atoms to rotate around bond axis. A pi bond is a side-to-side overlap of orbitals, which produces electron density regions distributed above and below the bond axis. The necessity of the fundamental concept of atomic orbital hybridization can be illustrated with a consideration of the element carbon. As a neutral bonding element, carbon can form four bonds; for example, four single bonds in the molecule methane, CH4. Hybridization of one s-orbital with three p-orbitals results in four equivalent energy orbitals, which point to the corners of a tetrahedral shape. Since all four hybridized orbitals have equal energy, the four valence electrons are distributed singly in each orbital and are available for single bond formation.
