chemical Bond

Bond, chemical, link that holds atoms together in compounds. The theory that atoms consist of electrons orbiting in shells around the nucleus led to an explanation of chemical bonding, which had first been noted in the nineteenth century. Atoms combine to achieve highly stable filled outer shells containing 2, 8, or 18 electrons, either by transfer of electrons from one atom to the other (ionic bond) or by the sharing of one electron from each atom such that both electrons orbit around both nuclei (covalent bond). The energy and length of chemical bonds, as well as the angles between them, may be investigated by spectroscopy and X-ray diffraction.

See also: Atom; Chemistry.