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Atomic weight = 30.9738 15P Electron configuration = [Ne]3s23p3 | |
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The most stable form of phosphorus at 25oC and 1 atmosphere pressure is white phosphorus. This allotrope changes into red phosphorus when heated in the absence of air. The structure of both forms of phosphorus is tetrahedral P4 molecules. White phosphorus burns in a limited supply of oxygen to form P4O6. When phosphorus burns in an excess of oxygen, it forms P4O10. The latter compound is the acid anhydride of phosphoric acid, H3PO4. When phosphoric acid is heated, it undergoes a condensation reaction where two molecules of phosphoric acid combine to form a larger molecule (pyrophosphoric acid) with the elimination of water: 2H3PO4 ---> H4P2O7 + H2O The most important polyphosphate is adenosine triphosphate, ATP, found in every living cell. | |