bromine

Name bromine
Symbol Br
Atomic Weight 79.904
Atomic Number 35
CAS ID 7726-95-6
Group Number 17
Group Name Halogen
Period Number 4
Origin of Name Greek, bromos - "stench."
Year Discovered 1826
Discovery Credits A. J. Balard at Montpellier, France and C. Lowig at Heidelberg in Germany.
Class Non-Metallic
Color Red-brown, metallic luster when solid
Standard State Liquid at 77 F & 298 K
Description Deep red, dense, sharp smelling liquid, Br2. Compounds used in fuel additives, pesticides, flame-retardants, and photography. Bromine is recovered from sea water and oil field brines.

Diagnostic tests: 
Bromine salts (along with F, Cl, and I) will give a blue color to flames when heated on a copper disk.
Treatment of the salt with concentrated H2SO4 acid will effervesce with the evolution of a brown gas (Br2). Bromine is always found associated with chlorine or iodine so a precipitate with AgNO3 solution is white (AgCl), cream (AgBr), or yellow (AgI) depending on which anion predominates.

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