Rhenium - chemistry.

Rhenium - chemistry. Rhenium, symbol Re, rare, silvery white, metallic element. The atomic number of rhenium is 75. Rhenium is one of the transition elements of the periodic table (see Periodic Law). The existence of rhenium and the similarity of its chemical properties to those of the element manganese were predicted in 1871 by the Russian chemist Dmitry Ivanovich Mendeleyev, who named it dvi-manganese. Rhenium was discovered in 1925 by the German chemists Walter Karl Noddack, Ida Eva Tacke Noddack, and Otto Berg in the ores tantalite, wolframite, and columbite by means of X-ray spectrographic analysis. It was later found in larger quantities in molybdenite. The element's name comes from Rhenus, the Latin name for the Rhine River. Rhenium metal is very hard; with the exception of tungsten, it is the least fusible of all common metals. It is extremely rare, ranking about 79th in natural abundance among elements in crustal rocks. Rhenium melts at about 3186°C (about 5767°F) and boils at about 5596°C (about 10,105°F). It has a specific gravity of 21.02, nearly twice that of lead. The atomic weight of rhenium is 186.207. Rhenium is used in electrical filaments, welding rods, thermocouples, cryogenic magnets, airplane engines, and photographic flashbulb filaments; it is also used as a catalyst. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.