bromine

1. N a pungent dark red volatile liquid element of the halogen series that occurs in natural brine and is used in the production of chemicals, esp ethylene dibromide. Symbol: Br; atomic no: 35; atomic wt: 79.904; valency: 1, 3, 5, or 7; relative density 3.12; density (gas): 7.59 kg/m³; melting pt: –7.2°C; boiling pt: 58.78°C 溴