Rhenium
Rhenium, the 75th element, is special because its melting point of 3181.85 degrees C
is third only to tungsten and carbon. It also boils at 5596.85 degrees C. It has an atomic mass of
186.2 amu, and a specific gravity of 21.02. Its e- levels are 2-8-18-32-13-2.
It is in group 7B (group 7), and has been known to have valences of +7, 4, 6, 2, and -1.
It was discovered in 1925 by W. Noddack, I. Tack, and O. Berg of Germany. Re is
usually alloyed with tungsten and platinum, and is used for making filaments in
mass spectrometers. It is found in platinum ores and in columbite (a niobium ore),
gadolinite (a gadolinium ore), and molybdenite (a molybdenum ore). It does not occur
free in nature, and there are 2 stable and 18 radioactive isotopes. Re is silvery-white with a metallic luster. Its density
is fourth to platinum, iridium, and osmium. Rhenium is very ductile, and little is known about
Re's toxicity.
May 20, 1997
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