Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Earth. It has a concentration in the Earth's crust of about one gram per kilogram (compare copper at about 0. 06 grams). In minerals, phosphorus generally occurs as phosphate.

Elemental phosphorus was first isolated as white phosphorus in 1669. In white phosphorus, phosphorus atoms are arranged in groups of 4, written as P4. White phosphorus emits a faint glow when exposed to oxygen – hence the name, taken from Greek mythology, Φωσφόρος meaning 'light-bearer' (Latin Lucifer), referring to the "Morning Star", the planet Venus. The term phosphorescence, meaning glow after illumination, derives from this property of phosphorus, although the word has since been used for a different physical process that produces a glow. The glow of phosphorus is caused by oxidation of the white (but not red) phosphorus — a process now called chemiluminescence. Phosphorus is classified as a pnictogen, together with nitrogen, arsenic, antimony, bismuth, and moscovium.

Phosphorus is an element essential to sustaining life largely through phosphates, compounds containing the phosphate ion, PO43−. Phosphates are a component of DNA, RNA, ATP, and phospholipids, complex compounds fundamental to cells. Elemental phosphorus was first isolated from human urine, and bone ash was an important early phosphate source. Phosphate mines contain fossils because phosphate is present in the fossilized deposits of animal remains and excreta. Low phosphate levels are an important limit to growth in a number of plant ecosystems. The vast majority of phosphorus compounds mined are consumed as fertilisers. Phosphate is needed to replace the phosphorus that plants remove from the soil, and its annual demand is rising nearly twice as fast as the growth of the human population. Other applications include organophosphorus compounds in detergents, pesticides, and nerve agents.

© Wikipedia | CC-by-SA-3.0 | Read more …

Atomic properties

Standard atomic weight30.9737 ±5·10-9
Atomic mass30.9737 u

Atomic radii

Radius (empirical)100 pm
Radius (calculated)98 pm
Covalent radius107 ±3 pm
Van der Waals radius180 pm

Atomic shell

Electron configurationNe 3s2 3p3
Ionization energy(1st) 10.486686 eV
(2nd) 19.76949 eV
(3rd) 30.20264 eV
(4th) 51.44387 eV
(5th) 65.02511 eV
Shell model

Physical properties

Densitywhite: 1.83 g·cm−3
red: 2.2 [2 … 2.4] g·cm−1
black: 2.69 g·cm−1
Molar volume1.702·10-5 m3·mol−1


Melting point317.3 K
Boiling point553.7 K
Liquid range236.4 K
Sublimation point689.2 [689.2 … 863] K
Transition temperature18 K


Melting enthalpy0.64 kJ·mol-1
Enthalpy of vaporization12.4 kJ·mol-1
Binding energy315 kJ·mol-1

Heat and conductivity

Specific heat capacity685.6 J·kg−1·K−1 (298 K)
Thermal conductivity0.236 W·m-1·K-1

Elastic properties

Bulk modulus11 GPa

Electrical properties

Resistance1·10-7 Ωm


Magnetic susceptibility-2.08·10-5 cm3·mol−1 (293 K)

Optical properties

Refractive index1.001

Chemical properties

Basicityslightly acidic
Oxidation state±3, 4, 5


Pauling scale2.19
Sanderson scale2.52
Allred-Rochow scale2.06
Mulliken scale2.3
Allen scale2.253
Ghosh-Gupta scale6.34 eV
Boyd-Edgecombe scale2.17
Nagle scale2.22
Pearson absolute negativity5.62 eV

Other properties

Natural occurrenceprimordial
Crystal structureOrthorhombic
Goldschmidt Classificationlithophile
Superconductorwith transition tempperature under special conditions
Price/kg2.69 USD

Natural abundances

7,000 ppb ≈ 7.03·1013 M☉
7,000 ppb ≈ 1.39·1013 Mt
1.1·106 ppb ≈ 1.1 kg
Earth’s crust
1·106 ppb ≈ 2.77·107 Mt
70 ppb ≈ 95.9 Gt
Flowing water
20 ppb ≈ 320 kt
Human body
1.1·107 ppb ≈ 769 g