Phosphorus

Phosphorus is a chemical element with the symbol P and atomic number 15. It belongs to the group of pnictogens and occurs in several allotropes, including white, red, and black phosphorus. White phosphorus is a waxy, translucent solid that is highly reactive and glows faintly in the dark when exposed to air; red phosphorus is more stable and less reactive; black phosphorus is the most thermodynamically stable form and has layered, semi-metallic properties.

Phosphorus is never found free in nature due to its high reactivity. It occurs mainly in minerals such as apatite and phosphorite and is obtained industrially from phosphate rock.

In biology, phosphorus is essential for life. It forms phosphate esters in DNA, RNA, and ATP, and is a key component of phospholipids and bone mineral as calcium phosphate.

Industrial production: reduction of phosphate ore with carbon and silica in electric furnaces yields white phosphorus, which can be converted to red phosphorus by heat. The dominant use is as fertilizer; phosphate rock mining supplies phosphate fertilizers for agriculture. Other uses include chemicals, detergents (historically), and flame retardants.

Safety and environment: white phosphorus is highly toxic and spontaneously inflames in air; it is stored under water to prevent ignition and exposure. Handling requires strict safety precautions.

History and name: discovered by Hennig Brand in 1669 from urine; the name derives from Greek phos (light) and pheros (bearer).