phosphorus
noun
- Archaic any phosphorescent substance or object
- a nonmetallic chemical element, normally a white, phosphorescent, waxy solid, becoming yellow when exposed to light: it is poisonous and unites easily with oxygen, so that it ignites spontaneously at room temperature: when heated in sealed tubes it is converted into a red form, which is nonpoisonous and less flammable than the white: when heated under a pressure of 10,000 atmospheres it is converted into a black powder: symbol, P; at. no., 15: a radioactive isotope () is used in the diagnosis and treatment of certain diseases, as a tracer in chemical and biochemical research, etc.
See phosphorus in American Heritage Dictionary 4
(fŏsˈfər-əs)
noun- Symbol P A highly reactive, poisonous, nonmetallic element occurring naturally in phosphates, especially apatite, and existing in three allotropic forms, white (or sometimes yellow), red, and black. An essential constituent of protoplasm, it is used in safety matches, pyrotechnics, incendiary shells, and fertilizers and to protect metal surfaces from corrosion. Atomic number 15; atomic weight 30.9738; melting point (white) 44.1°C; boiling point 280°C; specific gravity (white) 1.82; valence 3, 5. See Table at element.
- A phosphorescent substance.
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