Discovered in 1669, phosphorus exists in three common allotropes:

  1. White phosphorus is a white, waxy substance. It is soft, very reactive and consists of P4 molecules. It is so unstable that it turns yellow (as shown above) then reddens in light, and glows in the dark - hence "phosphorescence". It is the most volatile and explosive of the three basic allotropic forms. Hence white phosphorus is kept under water to isolate it from the air. This allotropic form of phosphorus is also the most useful in the production of other compounds of phosphorus.
  2. Red phosphorus, as shown above, is formed by exposing white phosphorus to sunlight or heating it under pressure to above 275oC. This form is fairly stable, but the heat from simple friction is enough to convert it to explosive white phosphorus. This feature is used to great advantage in the manufacture of safety matches.
  3. Black phosphorus is also produced by heating white phosphorus in the presence of a mercury catalyst and a seed crystal of black phosphorus. Black phosphorus is the least reactive, does not ignite easily and has the least commercial value.

Phosphorus is wide-spread throughout the world in rock structures such as phosphate rock (Ca3(PO4)2) and the apatites. Guano deposits found on islands frequented by sea birds are also an important source of phosphorus. The element is obtained industrially by the heating phosphate rock in sand (SiO2) and coke (carbon) in an electric furnace of 1450oC. The phosphorus produced is P4 and collected under water as white phosphorus.

Phosphorus is a nonmetal. The most common form of phosphorus, as well as some of its compounds, are noted for their ability to glow in the dark. Phosphorus produced today are used in:

Phosphorus is an essential constituent of the living tissue and bones. It plays a very important part in metabolic processes (as adenosine triphosphate), muscle action and hardening on bones and teeth (as hydroxyapatite).

BCIT Chemistry Resource Center