(From the Latin Phosphorus, the morning star Venus) A paramagnetic nonmetallic chemical element, normally a white, phophorescent, waxy solid, becoming yellow when exposed to light. It is poisonous and unites easily with oxygen, so it ignites spontaneously at room temperature. When heated in sealed tubes it is converted into a red form, which is nonpoisonous and less flammable than the white. When heated under a pressure of 10,000 atmospheres it is converted into a black powder.

Symbol: P
Atomic number: 15
Atomic weight: 30.973761
Density (at room temperature and pressure): 1.82 g/cc (white)
Melting point: 44.15°C
Boiling point: 280°C
Valence: -3, +3, +5
Ground state electron configuration: [Ne]3s23p3

See also: phosphorus-32