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