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