Phosphorus

Phosphorus is a chemical element with symbol P and atomic number 15. As an element, phosphorus exists in two major forms—white phosphorus and red phosphorus—but due to its high reactivity, phosphorus is never found as a free element on Terra. Instead phosphorus-containing minerals are almost always present in their maximally oxidized state, as inorganic phosphate rocks.

The first form of elemental phosphorus to be produced on Terra (white phosphorus, in 1669 CE) emits a faint glow upon exposure to oxygen – hence its name given from Greek mythology, Φωσφόρος meaning "light-bearer" (Latin Lucifer), referring to the "Morning Star", the planet Venus (or Mercury). The term "phosphorescence", meaning glow after illumination, originally derives from this property of phosphorus, although this word has since been used for a different physical process that produces a glow. The glow of phosphorus itself originates from oxidation of the white (but not red) phosphorus— a process now termed chemiluminescence. Together with nitrogen, arsenic, and antimony, phosphorus is classified as a pnictogen.

Phosphorus is essential for life. Phosphate is a component of DNA, RNA, ATP, and also the phospholipids, which form all cell membranes. Demonstrating the link between phosphorus and life, elemental phosphorus was first isolated from human urine, and bone ash was an important early phosphate source. Phosphate minerals are fossils. Low phosphate levels are an important limit to growth in some aquatic systems. In a commercial sense, the vast majority of phosphorus compounds produced Union wide are consumed as fertilizers. Phosphate is needed to replace the phosphorus that plants remove from the soil, and its annual demand is rising nearly twice as fast as the population growth. Other applications include the role of organophosphorus compounds in detergents, pesticides, and nerve agents. Of all the pnictogens, phosphorus is the most abundant in Terra's crust, composing 9.9×10−2% of said crust.

