Phosphorus (chemical symbol - P, from others-Greek. φῶς - light and φρρω — carrying, φωσφρρος — light-bearing; also from Lat. Phosphorus) is a chemical element of the 15th group (according to the outdated classification - the fifth group of the main subgroup, VA) of the third period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 15.
Phosphorus is one of the most common elements of the earth's crust: its content is 0.08-0.09% of its mass. The concentration in seawater is 0.07 mg/l[5]. In the free state, it does not occur due to high chemical activity. It forms about 190 minerals, the most important of which are apatite Ca5(PO4)3 (F,Cl,OH), phosphorite (Ca3(PO4)2) and others. Phosphorus is a part of the most important biological compounds - phospholipids. It is found in animal tissues, is part of proteins and other important organic compounds (ATP, DNA), is an element of life.
