Periodic Table of the Elements: Phosphorus

Name: Phosphorus
Symbol: P
Atomic Number: 15
Atomic Mass: 30.9738
Atomic Volume: 13.93 cc/mol
Discovered By: First isolated by Brand in 1669
Discovery Date: 1669
Origin of Name: Phosphorus - (Greek) phosphoros (light-bearing)
Toxicity: Yellow phosphorus is highly toxic; red has low toxicity. The inhalation of red phosphorus dust is as dangerous and has the same action as the inhalation of white phosphorus dust. Phosphine is particularly dangerous. It attacks the central nervous system and disturbs the blood circulation.
Summary: Phosphorus has three forms:

1. White - cubic crystals of P₄, melting point = 317.4 K, boiling point = 553.5 K, density = 1.828
2. Black - orthorhombic, density = 2.691
3. Red - red-violet powder, triclinic, sublimes at 689 K, density = 2.34

Phosphorus is not found free in nature, but usually as phosphates. Extremely toxic.

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