Discovered in 1925, rhenium was the last naturally occurring stable element to be discovered (francium was the last identified naturally occurring element, but it is unstable). Rhenium was named afterer Rhine. Nickel-based superalloys contain up to 6% of rhenium, chemical industry catalytic uses being next most important.
Rhenium is a silvery-white metal with one of the highest melting points of all elements, exceeded by only tungsten and carbon. It is also one of the densest, exceeded only by platinum, iridium and osmium.
Its usual commercial form is a powder, but this element can be consolidated by pressing and sintering in a vacuum or hydrogen atmosphere. This procedure yields a compact solid having a density above 90% of the density of the metal. When annealed this metal is very ductile and can be bent, coiled, or rolled. Rhenium-molybdenum alloys are superconductive at 10 K; tungsten-rhenium alloys are also superconductive around 4-8 K, depending on the alloy. Rhenium metal superconducts at 2.4 K.Rhenium has a stable isotope, rhenium-185, which nevertheless occurs in minority abundance, a situation found only in one other element (indium). Naturally occurring rhenium is 37.4% 185Re, which is stable, and 62.6% 187Re, which is unstable but has a very long half-life (~1010 years). This lifetime is affected by the charge state of rhenium atom. The beta decay of 187Re is used for rhenium-osmium dating of ores. The available energy for this beta decay (2.6 keV) is one of the lowest known among all radionuclides. There are twenty-six other recognized radioactive isotopes of rhenium.
The base value of each unit of ranges between 10 and 20Ð per unit, with up to 3 units being found at any one time.
Presence on Mars: Rare
|Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | Group 6|
|Group 3|||Antimony | Astatine | Barium | Bismuth | Cesium | Francium | Hafnium | Indium | Iodine | Iridium | Lanthanum | Lead | Mercury | |Osmium | Platinum | Polonium | Radium | Radon | Rhenium | Tantalum | Tellurium | Thallium | Tin | Tungsten | Xenon||