Phosphorus

March 1, 1999

Phosphorus has 15 protons, 15 electrons, and 16 neutrons. Phosphorus is a non-metal that is only twice as dense as water. At room temperature it is a waxy, white solid. Phosphorus was discovered by Hennig Brand in 1669. 

Phosphorus is made from calcium phosphate. Every year a few million tons are made. Phosphorus is used to make phosphoric acid for fertilizer.

Some detergents have phosphate, because phosphate softens water. But many places ban the use of phosphate detergents, since they cause lakes and rivers to have too many algae and other plants, and so make less oxygen in the water that kills animal life.

The chemistry of phosphorus is like that of nitrogen.

Phosphorus can be white or red. White is very reactive and catches fire in air. At temperatures below 35 C, white phosphorus glows in air. For safety, phosphorus is stored under water. 

Phosphate ion occurs in many compounds in living cells. Bones and teeth are made of calcium phosphate. About 20% of the skeleton is calcium phosphate. Phosphate bonds of AMP and ATP store energy for the body. Phosphate is also part of DNA.