Phosphorus is a poisonous, nonmetallic element found in phosphates. It is a very active element, combining easily with many other elements.
Phosphorus was discovered in the mid-1600s by German alchemist Hennig Brand (c.1630-c.1710). Alchemists were the forerunners of modern chemists. Brand was searching for the philosopher's stone, a magical substance that alchemists thought would transform common metals into pure gold. Brand became convinced that the human body must contain such an agent. He evaporated the water from some urine and burned the concentrated residue, along with some sand. Instead of the philosopher's stone, Brand produced a white, waxy substance that mysteriously glowed in the dark and ignited spontaneously when exposed to air. He named the substance phosphorus after the Greek word for "light-bearer."
Phosphorus is found in animal bones, which have long been used in fertilizing crops. Scientists learned in the early 1800s that the phosphorus found in bones was far more effective as a fertilizer when treated with sulfuric acid to make it soluble in water. The product is called superphosphate, and it can also be produced from mineral phosphate rock. Superphosphate is still in use today, along with a stronger version that supplies more than twice as much phosphorus nutrient.
Plants use phosphorus for photosynthesis (the process by which they make their food). They also need it to establish roots and to mature and ripen. But when phosphorus fertilizers drain into rivers and lakes, the nutrient stimulates the growth of algae, which consume the available oxygen and suffocate fish and other animals. In the human body, most phosphorus exists in the bones and teeth.
Phosphorus exists in several allotropic forms. Allotropes are forms of an element with different physical and chemical properties. The most common allotropes of phosphorus are white, red, and black phosphorus. White phosphorus exhibits the phenomenon of phosphorescence--it glows in the dark when exposed to air. It is one of the most dangerous substances known, and it is so reactive that it must be stored underwater or it will ignite spontaneously. It can also cause serious burns if touched. Still, white phosphorus is used to make such common products as detergents, water softeners, animal food, insecticides, steel, and plastics. It is also a component of explosives such as grenades and mortar shells. White phosphorus is also used to make the strike-anywhere safety match.