Bromine structure. The halogens darken in colour as the group is descended: fluorine is a very pale yellow gas, chlorine is greenish-yellow, and bromine is a reddish-brown volatile liquid that melts at −7.2 °C and boils at 58.8 °C. (Iodine is a shiny black solid.) This trend occurs because the wavelengths of visible light absorbed by the halogens increase down the group. Specifically, the colour of a halogen, such as bromine, results from the electron transition between the highest occupied antibonding "π" molecular orbital and the lowest vacant antibonding "σ" molecular orbital. The colour fades at low temperatures, so that solid
Bromine trifluoride Bromine trifluoride Bromine trifluoride is an interhalogen compound with the formula BrF. It is a straw-coloured liquid with a pungent odor. It is soluble in sulfuric acid but reacts violently with water and organic compounds. It is a powerful fluorinating agent and an ionizing inorganic solvent. It is used to produce uranium hexafluoride (UF) in the processing and reprocessing of nuclear fuel. Bromine trifluoride was first described by Paul Lebeau in 1906, who obtained the material by the reaction of bromine with fluorine at 20 °C: The disproportionation of bromine monofluoride also gives bromine trifluoride: Like ClF and IF, the