Rhenium
Symbol: Re
Atomic Number: 75
Atomic Weight: 186.207
Boiling Point: 58.70 K
Melting Point: 3455 K
Density at 300K: 21.0 g/cm3
Covalent radius: 1.28
Atomic radius: 1.97
Atomic volume: 8.85 cm3/mol
First ionization potental: 7.88 V
Specific heat capacity: 0.137 Jg-1K-1
Thermal conductivity: 47.9 Wm-1K-1
Electrical conductivity: 5.8*106Ω-1m-1
Heat of fusion: 33.05 kJ/mol
Heat of vaporization: 707.1 kJ/mol
Electronegativity: 1.9 (Pauling's)

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(From the Latin Rhenus, the river Rhine) A very rare, metallic chemical element that is a silver-white solid or a gray-to-black powder. Its density is exceeded only by that of platinum, iridium, and osmium; and its melting point is exceeded only by that of tungsten and carbon. Rhenium does not occur freely in nature, but is found in small amounts in gadolinite and molybdenite. Commercial production of rhenium is by extraction from the flue dusts of molybdenum smelters. Rhenium is used as a trace alloying agent for hardening metal compounds that are subjected to continuous frictional forces. It is mixed with tungsten or platinum to make filaments for mass spectrographs. It is also used as an electrical contact material as it has good resistance to wear and withstands arc corrosion. Rhenium catalysts are exceptionally resistant to poisoning and are used for the hydrogenation of fine chemicals. The metal and its alloys are also used in thermocouples and in electrical components. Rhenium resists corrosion and oxidation but slowly tarnishes in moist air. It is not soluble in hydrochloric acid and dissolves only slowly in other acids.

Rhenium was discovered in 1925 by Ida and Walter Noddack and Otto Carl Berg in Berlin, Germany but was predicted in 1869 by Dmitri Mendeleev as chemically related to manganese.

Symbol: Re
Atomic number: 75
Atomic weight: 186.207
Density (at room temperature and pressure): 21.02 g/cc
Melting point: 3,180°C
Boiling point: 5,627°C
Main valences: +3, +4, +5, +7
Ground state electron configuration: [Xe]4f145d56s2

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