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Some of our finest [ about ] Approved Articles Developed Articles (over 800) Share your knowledge. It's a way to achieve immortality. —Often attributed to the Dalai Lama Article of the Week [ about ] Phosphorus is a chemical element with the atomic number Z = 15. Unlike other elements in group VA of the periodic table, phosphorus is never found as a pure element in nature, but only in combination with other elements. It is present in all living organisms in the form of organophosphates and as calcium phosphates such as hydroxyapatite (Ca10(PO4)6(OH)2) and fluoroapatite (Ca10(PO4)6F2), substances found in teeth and bones. Many cell signaling cascades in living organisms operate by a series of phosphorylation events in which a phosphate group (PO4)2− is either added to a protein by a kinase or removed from a protein by a phosphorylase. Both red phosphorus and tetraphosphorus trisulfide are used in common matches because they are easily ignited by heat. However, the agricultural industry is the largest user of phosphorus in the form of fertilizers. The radioactive isotope 32P is used to radiolabel compounds for scientific studies. Phosphorus and arsenic share many chemical properties. Production of elemental phosphorus Calcium phosphate (phosphate rock), mostly mined in Florida and North Africa, can be heated to 1200-1500 Celsius with sand, which is mostly SiO2, and coke (impure carbon) to produce vaporized tetraphosphorus, P4, (mp. 44.2 C) which is subsequently condensed into a white power under water to prevent oxidation. Even under water, white phosphorus is slowly converted to the more stable red phosphorus allotrope (mp. 597C). Both the white and red allotropes of phosphorus are insoluble in water.[more...] New Draft of the Week [ about ] Hirohito (裕仁) or the Showa Emperor (昭和天皇 Shoowa Tennoo, 1901-1989) was the 124th emperor of Japan, 1926-89, and had the longest reign. He was the symbolic leader of his nation through prosperity (1926-29), the Great Depression (1929-41), victory and defeat in World War II (1941-45), the American Occupation (1945-50), and the rapid recovery of Japan to become an economic superpower (1950-86).[more...]