Phosphorus

Phosphorus (chemical symbol: P) is a chemical element with atomic number 15. It belongs to the nitrogen group of the periodic table. In nature, it does not occur as a free element, but is found in combined form, usually as phosphate (PO4).

Phosphorus is part of all living organisms. It is found in DNA and RNA, in the molecules responsible for memory storage, and in ATP, the molecule that carries energy for the cell. It is also a component of bones and teeth, where it combines with calcium to form hard mineral matter.

Forms and varieties

Phosphorus has several allotropic forms—the same element with different structures. The most common are white phosphorus, red phosphorus, and black phosphorus. White phosphorus is highly reactive and ignites easily in air; it is stored underwater. Red phosphorus is stable and is used industrially, such as in matchbox tips.

History of discovery

Phosphorus was identified in the 17th century, discovered through the chemical processing of bone ash. Its name comes from Greek, meaning 'light-bearer', because its white form gives off a faint glow when it reacts with oxygen in air.

Uses and agriculture

The most widespread use is in agriculture. Phosphate deposits are mined and used to make fertilizers that plants need in order to grow. Phosphorus is also used in detergents, pharmaceuticals, and chemical manufacturing. There are also military and other applications involving certain phosphorus compounds.

Biogeochemical cycle

Phosphorus cycles through soil, water, and living organisms. Unlike nitrogen, its cycle lacks a significant gas phase. When large amounts of phosphate enter rivers and lakes—usually from agriculture or wastewater—it increases algae growth, which depletes the oxygen in water; this is called eutrophication.