Ruthenium - Ru General Information Discovery Ruthenium was discovered by J.A. Sniadecki in 1808 in Poland, but not recognised as an element. Klaus is generally recognised as the discoverer, as in 1844 he purified the metal from the impure oxide. Appearance Ruthenium is a hard, lustrous, white metal that does not tarnish at room temperature. Source Ruthenium is found as the free metal but also associated with other platinum metals in the mineral pentlandite, found in the USA, and pyroxinite, found in South Africa. Commercially, it is obtained from the wastes of nickel refining. Uses Ruthenium is one of the most effective hardeners for platinum and palladium, and is alloyed with these metals to make electrical contacts for severe wear resistance. It is also a versatile catalyst, used to split hydrogen sulfide for example. Biological Role Ruthenium has no known biological role. Ruthenium(IV) oxide is highly toxic. General Information Ruthenium is unaffected by air, water and acids but reacts with molten alkali, and is attacked by halogens.

	Physical Information
	Atomic Number		44
	Relative Atomic Mass (12C=12.000)		101.07
	Melting Point/K		2583
	Boiling Point/K		4173
	Density/kg m-3		12370 (293K)
	Ground State Electron Configuration		[Kr]4d75s1
	Electron Affinity(M-M-)/kJ mol-1		-146

	Key Isotopes
	nuclide	96Ru	97Ru	98Ru	99Ru	100Ru
	atomic mass	95.91		97.91	98.91	99.90
	natural abundance	5.52%	0%	1.88%	12.7%	12.6%
	half-life	stable	2.88 days	stable	stable	stable
	nuclide	101Ru	102Ru	103Ru	104Ru	106Ru
	atomic mass	100.9	101.9		103.91
	natural abundance	17%	31.6%	0%	18.7%	0%
	half-life	stable	stable	39.6 days	stable	367 days

Other Information
Enthalpy of Fusion/kJ mol-1		23.7
Enthalpy of Vaporisation/kJ mol-1		567
Oxidation States
main	Ru+3
others	Ru-2, Ru0, Ru+1, Ru+2,
	Ru+4, Ru+5, Ru+6, Ru+7,
	Ru+8

	Ionisation Energies/kJ mol-1
	M - M+	711
	M+ - M2+	1617
	M2+ - M3+	2747
	M3+ - M4+	4500
	M4+ - M5+	6100
	M5+ - M6+	7800
	M6+ - M7+	9600
	M7+ - M8+	11500
	M8+ - M9+	18700
	M9+ - M10+	20900