• A nonmetallic chemical element whose atomic number is 15. It has three allotropic forms, one consists of white or colorless crystals, another of a black solid resembling graphite, and the third is a red to violet powder. White phosphorous is poisonous, ignites spontaneously in air, and is phosphorescent. Red phosphorous is more stable and is used in semiconductors and electroluminescent coatings. Black phosphorous is electrically conductive. Phosphorus has about 20 known isotopes, of which one is stable. Its chemical symbol is P.
  • chemical symbol P

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