Ruthenium

Ruthenium - Ru

CAS: 7440-18-8
Description: Hard, brittle, silvery metal
Classification: Transition Metal
Date of Discovery: 1844
Discoverer: Karl Klaus
Name Origin: Latin Ruthenia, "Russia"

Atomic Number: 44
Number of Neutrons: 57
Atomic Mass: 101.07(2) amu
Melting Point: 2334 °C
Boiling Point: 4150 °C
Density (293 K): 12.41 g/cm³
Atomic volume: 8.3 cm³/mol
Electrical resistivity: 0.137 10^-6/cm

Thermal conductivity: 1.17 W/cmK
Enthalpy of atomization: 603 kJ/mol (est.)
Enthalpy of vaporization: 595.0 kJ/mol
Enthalpy of fusion: 24.0 kJ/mol
Specific heat capacity: 0.238 J/gK

Energy levels: 2-8-18-15-1
Electron configuration: [Kr]4d⁷5s¹
Crystal Structure: Hexagonal
Atomic radius: 1.89 Å
Covalent radius: 1.25 Å
Oxidation States: 0, +1 through +8
Electronegativity, Pauling: 2.2
Electron affinity: 1.05 eV
First ionization energy: 7.37 eV
2nd ionization energy: 16.76 eV
3rd ionization energy: 28.47 eV
Polarizability: 9.6 10^-24cm³

Isotope	Natural Abundance	Atomic Mass	Half-life	Decay Mode	Spin
⁸⁸Ru
⁸⁹Ru	88.936	⁺
⁹⁰Ru	89.9298	11 s	⁺
⁹¹Ru	90.9264	9 s	⁺; EC	9/2+
⁹²Ru	91.9201	3.7 m	⁺	0+
^93mRu	10.8 s	IT; ⁺	1/2-
⁹³Ru	92.9171	1.0 m	⁺; EC	9/2+
⁹⁴Ru	93.91137	52 m	EC
⁹⁵Ru	94.91042	1.64 h	EC; ⁺	5/2+
⁹⁶Ru	5.52(6)	95.90760	Stable	0+
⁹⁷Ru	96.90756	2.89 d	EC	5/2+
⁹⁸Ru	1.88(6)	97.90529	Stable	0+
⁹⁹Ru	12.7(1)	98.905939	Stable	5/2+
¹⁰⁰Ru	12.6(1)	99.904219	Stable	0+
¹⁰¹Ru	17.0(1)	100.905582	Stable	5/2+
¹⁰²Ru	31.6(2)	101.904349	Stable	0+
¹⁰³Ru	102.906233	39.27 d	^-	3/2+
¹⁰⁴Ru	18.7(2)	103.905430	Stable	0+
¹⁰⁵Ru	104.907750	4.44 h	^-	3/2+
¹⁰⁶Ru	105.90733	1.020 y	^-	0+
¹⁰⁷Ru	106.9099	3.8 m	^-	0+
¹⁰⁸Ru	107.9102	4.5 m	^-
¹⁰⁹Ru	108.91320	34.5 s	^-
¹¹⁰Ru	109.9140	15 s	^-
¹¹¹Ru	110.9176	1.5 s	^-
¹¹²Ru	111.9188	4.5 s	^-
¹¹³Ru	112.9225	2.7 s	^-
¹¹⁴Ru	113.9239	0.57 s	^-
¹¹⁵Ru	114.928	0.74 s	^-
Berzelius and Osann in 1827 examined the residues left after dissolving crude platinum from the Ural mountains in aqua regia. While Berzelius found no unusual metals, Osann thought he found three new metals, one of which he named ruthenium. In 1844 Klaus, generally recognized as the discoverer, showed that Osann's ruthenium oxide was very impure and that it contained a new metal. Klaus obtained 6 g of ruthenium from the portion of crude platinum that is insoluble in aqua regia. A member of the platinum group, ruthenium occurs native with other members of the group in ores found in the Ural mountains and in North and South America. It is also found along with other platinum metals in small but commercial quantities in pentlandite of the Sudbury, Ontario, nickel-mining region, and in pyroxinite deposits of South Africa. Natural ruthenium contains seven isotopes. Twenty-one other isotopes and isomers are known, all of which are radioactive. The metal is isolated commercially by a complex chemical process, the final stage of which is the hydrogen reduction of ammonium ruthenium chloride, which yields a powder. The powder is consolidated by powder metallurgy techniques or by argon-arc welding. Ruthenium is a hard, white metal and has four crystal modifications. It does not tarnish at room temperatures, but oxidizes in air at about 800 °C. The metal is not attacked by hot or cold acids or aqua regia, but when potassium chlorate is added to the solution, it oxidizes explosively. It is attacked by halogens, hydroxides, etc. Ruthenium can be plated by electrodeposition or by thermal decomposition methods. The metal 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. A ruthenium-molybdenum alloy is said to be superconductive at 10.6 K. The corrosion resistance of titanium is improved a hundredfold by addition of 0.1% ruthenium. It is a versatile catalyst. Hydrogen sulfide can be split catalytically by light using an aqueous suspension of CdS particles loaded with ruthenium dioxide. It is thought this may have application to removal of H₂S from oil refining and other industrial processes. Compounds in at least eight oxidation states have been found, but of these, the +2. +3. and +4 states are the most common. Ruthenium tetroxide, like osmium tetroxide, is highly toxic. In addition, it may explode. Ruthenium compounds show a marked resemblance to those of osmium. LINKS: Ruthenium oxide temperature sensors Ruthenium Tetroxide Staining Agent Selective Transformations of Alkynes with Ruthenium Catalysts Return Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998.

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