Phosphorus, ₁₅P

Forms of phosphorus Waxy white Red Red and violet Black
Phosphorus
Pronunciation	/ˈfɒsfərəs/ ⓘ ​(FOS-fər-əs)
Allotropes	white, red, violet, black and others (see Allotropes of phosphorus)
Appearance	white, red and violet are waxy, black is metallic-looking
Standard atomic weight Ar°(P)
	30.973761998±0.000000005[1] 30.974±0.001 (abridged)[2]
Abundance
in the Earth's crust	5.2 (silicon = 100)
Phosphorus in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson N ↑ P ↓ As silicon ← phosphorus → sulfur
Atomic number (Z)	15
Group	group 15 (pnictogens)
Period	period 3
Block	p-block
Electron configuration	[Ne] 3s2 3p3
Electrons per shell	2, 8, 5
Physical properties
Phase at STP	solid
Melting point	white: 317.3 K ​(44.15 °C, ​111.5 °F) red: ∼860 K (∼590 °C, ∼1090 °F)[3]
Boiling point	white: 553.7 K ​(280.5 °C, ​536.9 °F)
Sublimation point	red: ≈689.2–863 K ​(≈416–590 °C, ​≈780.8–1094 °F) violet: 893 K (620 °C, 1148 °F)
Density (near r.t.)	white: 1.823 g/cm3 red: ≈2.2–2.34 g/cm3 violet: 2.36 g/cm3 black: 2.69 g/cm3
Heat of fusion	white: 0.66 kJ/mol
Heat of vaporization	white: 51.9 kJ/mol
Molar heat capacity	23.824 J/(mol·K) (white)
Specific heat capacity	769.161 J/(kg·K) (white)
Vapor pressure (white) P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 279 307 342 388 453 549
vapor pressure (red) P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 455 489 529 576 635 704
Atomic properties
Oxidation states	common: −3, +3, +5 −2,[6] −1,[6] 0,[4] +1,[6][5] +2,[6] +4[6]
Electronegativity	Pauling scale: 2.19
Ionization energies	1st: 1011.8 kJ/mol 2nd: 1907 kJ/mol 3rd: 2914.1 kJ/mol (more)
Covalent radius	107±3 pm
Van der Waals radius	180 pm
Spectral lines of phosphorus
Other properties
Natural occurrence	primordial
Crystal structure	α-white: ​body-centered cubic (bcc) (cI232)
Lattice constant	a = 1.869 nm (at 20 °C)[7]
Crystal structure	black: ​orthorhombic (oS8)
Lattice constants	a = 0.33137 nm b = 1.0477 nm c = 0.43755 nm (at 20 °C)[7]
Thermal conductivity	white: 0.236 W/(m⋅K) black: 12.1 W/(m⋅K)
Magnetic ordering	white, red, violet, black: diamagnetic[8]
Molar magnetic susceptibility	−20.8×10−6 cm3/mol (293 K)[9]
Bulk modulus	white: 5 GPa red: 11 GPa
CAS Number	7723-14-0 (red) 12185-10-3 (white)
History
Naming	from the greek Φωσφόρος, meaning 'light-bearer'
Discovery	Hennig Brand (1669)
Recognised as an element by	Antoine Lavoisier[10] (1777)
Isotopes of phosphorus v e
Main isotopes[11] Decay Isotope abun­dance half-life (t1/2) mode pro­duct 31P 100% stable 32P trace 14.269 d β− 32S 33P trace 25.35 d β− 33S
Category: Phosphorus view talk edit | references

Phosphorus is a chemical element with symbol P and atomic number 15. It was first isolated by the alchemist Henning Brand in 1669, making it the first element to be discovered chemically.

Phosphorus is the second-lightest member of group 15 on the periodic table, often called the pnictogens. As an element, 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. With a concentration of 0.099%, phosphorus is the most abundant pnictogen in the Earth's crust. With few exceptions, minerals containing phosphorus are in the maximally oxidized state as inorganic phosphate rocks.

The first form of elemental phosphorus that was produced (white phosphorus, in 1669) 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 (or Mercury). The term "phosphorescence", meaning glow after illumination, originally derives from this property of phosphorus, although this word has since been used for a different physical process that produces a glow. The glow of phosphorus itself originates from oxidation of the white (but not red) phosphorus — a process now termed chemiluminescence. Together with nitrogen, arsenic, antimony, and bismuth, phosphorus is classified as a pnictogen.

Phosphorus is essential for life. Phosphates (compounds containing the phosphate ion, PO₄³⁻) are a component of DNA, RNA, ATP, and phospholipids. 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 some aquatic systems. The vast majority of phosphorus compounds produced 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.