Bromine diffusing in gas jars. Image 1 of 2. Bromine is a liquid that readily vaporizes at room temperature. The dark orange bromine vapour is seen moving up the gas jars. Bromine is part of the halogen group, and is the only nonmetallic element that is a liquid at room temperature. It is extremely toxic and takes its name from a Greek word meaning stench. Bromine compounds are used in water purification and textile flameproofing. For an image of bromine vapour fully diffused up the glass jars, see image A150/296.