phosphorus

Name phosphorus
Symbol P
Atomic Weight 30.973761
Atomic Number 15
CAS ID 7723-14-0
Group Number 15
Group Name Pnictogen
Period Number 3
Origin of Name Greek, phosphoros = "bringer of light."
Year Discovered 1669
Discovery Credits Discovered by Hennig Brandt at Hamburg, Germany
Class Non-Metallic
Color Red or Silvery White
Standard State Solid at 77 F & 298 K
Description White phosphorus (P4) is soft and flammable, red phosphorus is powdery and usually non-flammable. Neither form reacts with water or dilute acid but alkalis react to form phosphine gas. Used in fertilizers, insecticides, metal treatment, detergents, etc

Diagnostic tests: 
Compounds containing phosphates (PO43-) give a green flame test, especially after being moistened with sulfuric acid (H2SO4) although this test may be rendered unsatisfactory due to other coloring agents.
If a powdered sample is fused in a closed tube with metallic sodium or magnesium and afterward moistened with water, hydrogen phosphide is given off, recognized by its disagreeable odor.

Back to Elements Table Page