Phosphorus is commonly misspelled "phosphorous". It is an essential component of living systems and is found in nervous tissue, bones and cell protoplasm. Phosphorus exists in several allotropic forms including white (or yellow), red, and black (or violet). White phosphorus has two modifications. Ordinary phosphorus is a waxy white solid. When pure, it is colourless and transparent. It is insoluble in water, but soluble in carbon disulphide. It catches fire spontaneously in air, burning to P4O10, often misnamed as phosphorus pentoxide. When exposed to sunlight, or when heated in its own vapour to 250°C, it is converted to the red variety. This form does not ignite spontaneously and it is a little less dangerous than white phosphorus. The red modification is fairly stable and sublimes with a vapour pressure of 1 atmosphere at 417°C.
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Phosphorus is a key component of biological molecules such as DNA and RNA. Phosphorus is a component of bones, and teeth, and many other compounds required for life. Chronic poisoning of people working unprotected with white phosphorus leads to necrosis of the jaw ("phossy-jaw").
Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of phosphorus where known.
Phosphorus wasdiscovered by Hennig Brand in 1669 at Germany.Origin of name: from the Greek word "phosphoros" meaning "bringer of light" (an ancient name for the planet Venus?).
Isolation: originally, phosphorus was extracted from urine. However there is plenty of phosphorus in phosphate ores and those ores represent the usual source for commercially produced phosphorus. There is normally no need to make phosphorus in the laboratory as it is readily available commercially.
The usial route involves heating a phosphate with sand and carbon in an electric furnace. It is highly energy intensive.
Density of solid: 1823 kg m-3
Molar volume: 17.02 cm3
Thermal conductivity: 0.236 W m‑1 K‑1
Melting point: (white P) 317.3 [44.2 °C (111.6 °F)] K
Boiling point: 550 [277 °C (531 °F)] K
Enthalpy of fusion: 20.5 kJ mol-1
Atomic radius (empirical): 100 pm
Molecular single bond covalent radius: 111 (coordination number 3) ppm
van der Waals radius: 190 ppm
Pauling electronegativity: 2.19 (Pauling units)
Allred Rochow electronegativity: 2.06 (Pauling units)
Mulliken-Jaffe electronegativity: 2.30 (20% s orbital)
First ionisation energy: 1011.81 kJ mol‑1
Second ionisation energy: 1907.47 kJ mol‑1
Third ionisation energy: 2914.11 kJ mol‑1
Universe: 7000 ppb by weight
Crustal rocks: 1000000 ppb by weight
Human: 11000000 ppb by weight
