fosforem

Fosforem, known in English as phosphorus, with symbol P and atomic number 15, is a chemical element that is essential for life. The name derives from the Greek phōsphoros, meaning light-bringer, a reference to the glow of white phosphorus observed in the 17th century. At ambient conditions, fosforem exists in multiple allotropes, the most common being white, red, and black phosphorus.

Fosforem is abundant in the Earth's crust, primarily in phosphate minerals such as apatite. It is not found free in nature due to its high reactivity. Industrial production typically starts from phosphate rock. The wet process yields phosphoric acid for fertilizer manufacture, while a separate thermal process reduces phosphate with silica and carbon in an electric furnace to produce elemental phosphorus (as P4), used for chemicals and steelmaking.

White phosphorus consists of P4 molecules and is highly reactive and toxic, with a faint glow in the dark. Red phosphorus is produced by heating white phosphorus in the absence of air and is far less reactive, making it safer to handle. Black phosphorus is the most stable allotrope under certain conditions and has a layered, semiconducting structure of interest for materials science.

Biologically, fosforem is an essential macronutrient for all living organisms. It is a core component of nucleic acids (DNA and RNA), ATP, and phospholipids that form cell membranes. The phosphorus cycle describes its movement through soil, water, and living systems.

Applications include phosphate fertilizers, detergents, and food supplements; phosphorus compounds also serve in steelmaking as a deoxidizer and in the production of phosphors used in lighting and display technologies. Safety concerns are mainly associated with white phosphorus, which is highly toxic and can ignite in air; it is stored underwater to prevent ignition, while red and black phosphorus are comparatively less hazardous. The element was first isolated in 1669 by Hennig Brand.