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.
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) |
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) |