Rhenium - Re General Information Discovery Rhenium was discovered by W. Noddack, I. Tacke and O. Berg in 1925 in Berlin, Germany. Appearance Rhenium is a silvery metal which is usually obtained as a grey powder. Source Rhenium does not occur free in nature or as a compound in a mineral species. It is, however, widely spread throughout the Earth's crust to the extent of about 0.001 parts per million. Commercial production of rhenium is by extraction from the flue dusts of molybdenum smelters. Uses Rhenium is used as an additive to tungsten and molybdenum-based alloys to impart useful properties. It is widely used for filaments for mass spectrographs. It is also used as an electrical contact material as it has good wear resistance and withstands arc corrosion. Rhenium catalysts are exceptionally resistant to poisoning and are used for the hydrogenation of fine chemicals. Biological Role Rhenium has no known biological role. General Information Rhenium resists corrosion and oxidation but slowly tarnishes in moist air. It reacts with nitric and sulfuric acids.

	Physical Information
	Atomic Number		75
	Relative Atomic Mass (12C=12.000)		186.2
	Melting Point/K		3453
	Boiling Point/K		5900
	Density/kg m-3		21020 (293K)
	Ground State Electron Configuration		[Xe]4f145d56s2
	Electron Affinity(M-M-)/kJ mol-1		-37

	Key Isotopes
	nuclide	185Re	186Re	187Re	188Re
	atomic mass	184.9		186.9
	natural abundance	37.4%	0%	62.6%	0%
	half-life	stable	88.9 h	4x1010 yrs	16.7 h

Other Information
Enthalpy of Fusion/kJ mol-1		33.1
Enthalpy of Vaporisation/kJ mol-1		704.25
Oxidation States
main	Re+3, Re+4, Re+5
others	Re-3, Re-1, Re0, Re+1,
	Re+2, Re+6, Re+7

	Ionisation Energies/kJ mol-1
	M - M+	760
	M+ - M2+	1260
	M2+ - M3+	2510
	M3+ - M4+	3640
	M4+ - M5+	4900
	M5+ - M6+	6300
	M6+ - M7+	7600
	M7+ - M8+
	M8+ - M9+
	M9+ - M10+