Phosphorus - P General Information Discovery Phosphorus was discovered in 1669 by H. Brandt in Hamburg, Germany, by extraction from urine. Appearance Phosphorus occurs in three major forms, white (usually seen as yellow), red and black. The white form appears as a waxy white/pale yellow solid, but when pure is colourless and transparent. The red and black forms are powders of the appropriate colour. Source Phosphorus is not found free in nature, but is widely distributed in combination with minerals. An important source is phosphate rock, which contains the apatite minerals and is found in large quantities in the USA, the former USSR and elsewhere. White phosphorus may be made commercially by several methods. Usually phosphate rock is heated in the presence of carbon and silica in a furnace, which produces phosphorus as a vapour which is then collected under water. It can then be converted to red phosphorus by heating for several days. Uses Many fertilisers contain a high proportion of phosphorus and are manufactured from concentrated phosphoric acids. World wide demand for fertilisers has greatly increased in recent years as their importance to agriculture and arming has grown. Phosphorus is also important in the production of steel. Phosphates are ingredients of some detergents, but are increasingly being omitted nowadays due to concern that high phosphate levels in natural water supplies cause the growth of undesirable algae. Phosphates are also used in the production of special glasses and fine chinaware. Biological Role Phosphorus is the basis of life as part of the DNA molecule. White phosphorus is very toxic and contact with skin can cause severe burns. General Information White phosphorus is almost insoluble in water but soluble in carbon disulfide. It burns spontaneously in air above 30°C. When exposed to sunlight or heated in its own vapour to 250°C it is converted to red phosphorus, which is less dangerous than the white form and does not ignite spontaneously. Red phosphorus is used in the manufacture of safety matches, pesticides, incendiary shells, smoke bombs and tracer pellets.

	Physical Information
	Atomic Number		15
	Relative Atomic Mass (12C=12.000)		30.974
	Melting Point/K		317.3 (white), 683 (red)
	Boiling Point/K		553 (white)
	Density/kg m-3		1820 (white)
			2200 (red)
			2690 (black) all at 293K
	Ground State Electron Configuration		[Ne]3s23p3
	Electron Affinity(M-M-)/kJ mol-1		-60

	Key Isotopes
	nuclide	31P	32P	33P
	atomic mass	30.974	31.974	32.972
	natural abundance	100%	0%	0%
	half-life	stable	14.3 days	25 days

Other Information
Enthalpy of Fusion/kJ mol-1		2.51 (white)
Enthalpy of Vaporisation/kJ mol-1		51.9 (white)
Oxidation States
main	P+5
others	P-3, P-2, P0, P+2, P+3
Covalent Bonds /kJ mol-1
P - H	328
P - O	407
P = O	560
P - F	490
P - Cl	319
P - P	209

	Ionisation Energies/kJ mol-1
	M - M+	1011.7
	M+ - M2+	1903.2
	M2+ - M3+	2912
	M3+ - M4+	4956
	M4+ - M5+	6273
	M5+ - M6+	21268
	M6+ - M7+	25397
	M7+ - M8+	29854
	M8+ - M9+	35867
	M9+ - M10+	40958