10 Radon Facts (Rn or Atomic Number 86) Nonmetals Photo Gallery and Facts. The atomic number of phosphorus (P) is 15.The atomic weight of P is 30.973762 grams per mole.See the Web Links to below this answer for a periodic table with more information about this element! Arsenic, Antimony, Bismuth and Moscovium are the other elements in the nitrogen family. Phosphorus Facts (Atomic Number 15 or Element Symbol P) 10 Argon Facts - Ar or Atomic Number 18. The atomic weight of P is 30.973762 grams per mole. Chemical Element Pictures - Photo Gallery. All others have half-lives of under 2.5 minutes, most under a second. The atomic number of phosphorus (P) is 15. Phosphorus (P) is most commonly a white-yellow solid non metal in Group 15 of the periodic table. It has the atomic number 15. Phosphorus is a reactive nonmetal with element symbol P and atomic number 15. At 0.099%, phosphorus is the most abundant pnictogen in the Earthâ s crust. too small to affect Ar(P). See the Web Links to below this answer for a periodic table with more information about this element! None, phosphate is not an element Phosphate is an anion with the chemical formula PO_4^(3-) and has the above configuration. Although phosphorus (15 P) has 23 isotopes from 25 P to 47 P, only 31 P is stable; as such, phosphorus is considered a monoisotopic element. It is one of the essential elements in the human body and is widely encountered in products such as fertilizers, pesticides, and detergents. Atomic number of Phosphorus is 15 and it is indicated by the symbol is P. P belongs to the nitrogen family. The longest-lived radioactive isotopes are 33 P with a half-life of 25.34 days and 32 P with a half-life of 14.268 days. atomic mass of phosphorus. History of Chemical Matches. Magic Trick: Smoking Fingers. White phosphorous, red phosphorus and black phosphorus are three allotropes of phosphorous. Number of Energy Levels: 3: First Energy Level: 2: Second Energy Level: 8: Fourth Energy Level: 5 It has the symbol P. Only single elements have a atomic number, which is the number of protons in the nucleus. The atomic number of phosphorus is 15 and the atomic number of oxygen is 8. It is the 12 th most abundant element in Earth’s crust.