Phosphorus, P

Phosphorus is the chemical element that has the symbol P and atomic number 15. The name comes from the Greek: phôs (meaning "light") and phoros (meaning "bearer"). A multivalent nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks.

Due to its high reactivity, phosphorus is never found as a free element in nature on Earth. One form of phosphorus (white phosphorus) emits a faint glow upon exposure to oxygen (hence its Greek derivation and the Latin 'light-bearer', meaning the planet Venus as Hesperus or "Morning Star").

Phosphorus is a component of DNA and RNA and an essential element for all living cells. The most important commercial use of phosphorus-based chemicals is the production of fertilizers.

Phosphorus compounds are also widely used in explosives, nerve agents, friction matches, fireworks, pesticides, toothpaste, and detergents.

Technical Data
Symbol P Melting point / °C α-P4 44.1*
Atomic number 15 Boiling point / °C 280.5
No. of naturally occurring isotopes 1 Vapour pressure/ mm Hg 0.122(20°C)
Atomic weight 30.97376 Dielectric constant (20°C) 4.1(α-P4)
Electronic configuration [Ne]3s23p3 Ionization energy/kJmol-1 I 1012
Electrical resistivity (20°C)/μohm cm 1011(α-P4) Ionization energy/kJmol-1 II 1903
Refractive index nD (29.2°C) 1.8244 Ionization energy/kJmol-1 III 2912
Density (20°C)/gcm3 1.8232 (α-P4) *(44.25 when ultrapure)  
Evaporation Techniques
Temperature (oC) @Vap. Pressure Techniques Remarks
10-8 Torr 10-6 Torr 10-4 Torr Electron Beam Crucible Coil Boat
327 361 402 - Al2O3 - - Metal reacts violently in air.

P1-10000-P -100 mesh (red)