Connecting Chemistry


Atomic symbol: Br
Atomic number: 35
Atomic mass: 79.9

Appearance: Fuming red-brown liquid at 25°C

Group: 17
Period: 4
Series: Halogens (Reactive nonmetals)
Block: p
Electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵

Bromine and mercury are the only elements that are liquid at room temperature and pressure..

Bromine decolorization is used as a simple qualitative test for unsaturation. Bromine is a dark red-brown liquid, but alkenes and dibromoalkanes are colorless. When an alkene is combined with bromine, a dibromoalkanes is formed, and red-brown bromine quickly decolorizes.

Fun Fact! Sourced from marine molluscs, bromine is a major component in an ancient purple dye used in the dye industry of Ancient Rome.