Phosphorus - P
Chemical properties of phosphorus - Health effects of phosphorus - Environmental effects of phosphorus
Phosphorous is a multivalent nonmetal of the nitrogen group. It is found in nature in several allotropic forms, and is an essential element for the life of organisms.
There are several forms of phosphorous, called white, red and black phosphorous, although the their colours are more likely to be slightly different. White phosphorous is the one manufactured industrial; it glows in the dark, is spontaneously flammable when exposed to air and is deadly poison. Red phosphorous can vary in colour from orange to purple, due to slight variations in its chemical structure. The third form, black phosphorous, is made under high pressure, looks like graphite and, like graphite, has the ability to conduct electricity.
Concentrated phosphoric acids are used in fertilizers for agriculture and farm production. Phosphates are used for special glasses, sodium lamps, in steel production, in military applications (incendiary bombs, smoke screenings etc.), and in other applications as: pyrotechnics, pesticides, toothpaste, detergents.
Phosphorous in the environment
In the natural world phosphorous is never encountered in its pure form, but only as phosphates, which consists of a phosphorous atom bonded to four oxygen atoms. This can exists as the negatively charged phosphate ion (PO43-), which is how it occurs in minerals, or as organophosphates in which there are organic molecules attached to one, two or three of the oxygen atoms.
The amount of phosphorous that is naturally present in food varies considerably but can be as high as 370 mg/100 g in liver, or can be low, as in vegetable oils. Foods rich in phosphorous include tuna, salmon, sardines, liver, turkey, chicken, eggs and cheese (200 g/100 g).
There are many phosphate minerals, the most abundant being forms of apatite. Fluoroapatite provides the most extensively mined deposits. The chief mining areas are Russia, USA, Morocco, Tunisia, Togo and Nauru. World production is 153 million tones per year. There are concerns over how long these phosphorous deposits will last. In case of depletion there could be a serious problem for the worlds food production since phosphorus is such an essential ingredient in fertilizers.
In the oceans, the concentration of phosphates is very low, particularly at the surface. The reason lies partly within the insolubility of aluminum and calcium phosphates, but in any case in the oceans phosphate is quickly used up and falls into the deep as organic debris. There can be more phosphate in rivers and lakes, resulting in excessive algae growth. For further details go to environmental effects of phosphorous.
Back to the periodic table of elements.
For more information on phosphorus' place in the environment, move to the phosphorus cycle.