Phosphorus is quite commonchemical element on our planet. Its name translates as “luminous,” because in its pure form it glows brightly in the dark. This element was discovered by chance, by the alchemist Henning Brand, when he tried to extract gold from his urine. So phosphorus was the first element that the alchemists were able to extract through their experiments.
Phosphorus characteristic
He is chemically very active, so in naturecan be found only in the form of minerals - compounds with other elements, of which there are 190 species. The most important compound is calcium phosphate (mineral apatite). Many varieties of apatites are now known, the most common of which is fluorapatite. From apatites of various types, sedimentary rocks — phosphorites — are composed.
For living organisms, phosphorus is very important because it is a part of both plant and animal protein in the form of various compounds.
In plants, this element is containedmainly in the proteins of the seed, and in animals - in various proteins of the blood, milk, cells of the brain and nervous tissues. A large amount of phosphorus is found in the form of calcium phosphate in the bones of vertebrates.
Phosphorus exists in three allotropic modifications: white phosphorus, red and black. Let's look at them in more detail.
White phosphorus can be obtained if cooled quickly.his couples. Then a solid crystalline substance is formed, which in its pure form is absolutely colorless and transparent. White phosphorus, intended for sale, is usually painted in a slightly yellowish color and is very similar in appearance to wax. In the cold, this substance becomes brittle, and at temperatures above 15 degrees it becomes soft, and it can be easily cut with a knife.
White phosphorus does not dissolve in water, butlends itself well to organic solvents. It oxidizes very quickly in air (it starts to burn) and at the same time it glows in the dark. Actually, ideas about the luminous substance and detective stories about the Baskervilles dog are associated precisely with white phosphorus. It is a strong poison that acts deadly even in small doses.
Red phosphorus is a solid.dark red color, which is very different in its properties from that described above. It is oxidized in air, it is very slow, it does not glow in the dark, it lights up only when heated, it is impossible to dissolve it in organic solvents, and it is not poisonous. With strong heating, in which there is no air access, it is not melted, turns into steam, from which, upon cooling, white phosphorus is obtained. When both elements are burned, phosphorus oxide is formed, which proves the presence of the same element in their composition. In other words, they are formed by one element - phosphorus - and are its allotropic modifications.
Black phosphorus is obtained from white at 200 degreesCelsius under high pressure. It has a layered structure, metallic luster and looks similar to graphite. Of all the solid species of this substance, it is the least active.
Phosphorus application
Modern phosphorus production is about a million tons per year. Main producers: USA, Holland, Canada, Germany.
The main part of the extracted phosphorus is spent onproduction of thermal phosphoric acid, which is used in the production of fertilizers and phosphates. White phosphorus is used as a smoke-forming and incendiary agent, including for tracer ammunition.
Red is used to make the incendiary surface of a matchbox, and in the production of incandescent bulbs it acts as a gas absorber.
Phosphorus has found its application in metallurgy. It is used as an additive for the production of doped alloys, solders, magnetic and antifriction alloys.
