The S atoms have bonds with three Fe and one other S atom. The resulting electrically charged atom or molecule is called an ion. The negatively charged electron has a mass equal to of that of a hydrogen atom. Which reduces positive character of beta hydrogen atom. The ions or molecules surrounding the central atom are called ligands. A sphingolipid with an R group consisting of a hydrogen atom only is a ceramide. Exact analytical answers are available for the nonrelativistic hydrogen atom. Deuterated chloroform is an isotopologue of chloroform with a single deuterium atom. Hydroxocobalamin has a hydroxyl group attached to the cobalt atom. The reaction with alkyl halides leads to alkylation of the nitrogen atom. Another typical example is that of the particles in a nucleus of an atom. It is the volume "occupied" by an individual atom (or molecule). Another typical example is that of the nucleons in the nucleus of an atom. There is a set of quantum numbers associated with the energy states of the atom. VX is chiral at its phosphorus atom.