RUTHENIUM

Introduction

Atomic Number: 44
Group: 8 or VIII B
Atomic Weight: 101.07
Period: 5
CAS Number: 7440-18-8

Classification

Chalcogen
Halogen
Noble Gas
Lanthanoid
Actinoid
Rare Earth Element
Platinum Group Metal
Transuranium
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)

Description • Uses/Function

Berzelius and Osann in 1827 examined the residues left after dissolving crude platinum from the Ural mountains in aqua regia. While Berzeliusfound no unusual metals, Osann thought he found three new metals, one of which he named ruthenium. In 1844 Klaus, generally recognized as thediscoverer, showed that Osann’s ruthenium oxide was very impure and that it contained a new metal. Klaus obtained 6 g of ruthenium from the portionof crude platinum that is insoluble in aqua regia. A member of the platinum group, ruthenium occurs native with other members of the group in oresfound in the Ural mountains and in North and South America. It is also found along with other platinum metals in small but commercial quantitiesin 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 powdermetallurgy techniques or by argon-arc welding. Ruthenium is a hard, white metal and has four crystal modifications. It does not tarnish at roomtemperatures, 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 addedto the solution, it oxidizes explosively. It is attacked by halogens, hydroxides, etc. Ruthenium can be plated by electrodeposition or by thermaldecomposition methods. The metal is one of the most effective hardeners for platinum and palladium, and is alloyed with these metals to make electricalcontacts for severe wear resistance. A ruthenium-molybdenum alloy is said to be superconductive at 10.6 K. The corrosion resistance of titanium isimproved a hundredfold by addition of 0.1% ruthenium. It is a versatile catalyst. Hydrogen sulfide can be split catalytically by light using an aqueoussuspension of CdS particles loaded with ruthenium dioxide. It is thought this may have application to removal of H2S from oil refining and otherindustrial 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 thoseof osmium. The metal is priced at about $30/g (99.95% pure). 1

Physical Properties

Melting Point:2*  2334 °C = 2607.15 K = 4233.2 °F
Boiling Point:2* 4150 °C = 4423.15 K = 7502 °F
Sublimation Point:2 
Triple Point:2 
Critical Point:2 
Density:3  12.1 g/cm3

* - at 1 atm

Electron Configuration

Electron Configuration:  *[Kr] 5s1 4d7
Block: d
Highest Occupied Energy Level: 5
Valence Electrons: 

Quantum Numbers:

n = 4
ℓ = 2
m = -1
ms = -½

Bonding

Electronegativity (Pauling scale):4 2.2
Electropositivity (Pauling scale): 1.8
Electron Affinity:5 1.05 eV
Oxidation States: +4,3,6,8
Work Function:6 4.80 eV = 7.6896E-19 J

Ionization Potential   eV 7  kJ/mol  
1 7.3605    710.2
Ionization Potential   eV 7  kJ/mol  
2 16.76    1617.1
Ionization Potential   eV 7  kJ/mol  
3 28.47    2746.9

Thermochemistry

Specific Heat: 0.238 J/g°C 8 = 24.055 J/mol°C = 0.057 cal/g°C = 5.749 cal/mol°C
Thermal Conductivity: 117 (W/m)/K, 27°C 9
Heat of Fusion: 24 kJ/mol 10 = 237.5 J/g
Heat of Vaporization: 595 kJ/mol 11 = 5887.0 J/g
State of Matter Enthalpy of Formation (ΔHf°)12 Entropy (S°)12 Gibbs Free Energy (ΔGf°)12
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 6.82 28.53488 0 0
(g) 153.6 642.6624 44.550 186.3972 142.4 595.8016

Isotopes

Nuclide Mass 13 Half-Life 13 Nuclear Spin 13 Binding Energy
100Ru 99.9042195(22) STABLE 0+ 862.13 MeV
101Ru 100.9055821(22) STABLE 5/2+ 873.93 MeV
102Ru 101.9043493(22) STABLE 0+ 882.00 MeV
103Ru 102.9063238(22) 39.26(2) d 3/2+ 890.07 MeV
104Ru 103.905433(3) STABLE 0+ 898.14 MeV
105Ru 104.907753(3) 4.44(2) h 3/2+ 906.21 MeV
106Ru 105.907329(8) 373.59(15) d 0+ 914.28 MeV
107Ru 106.90991(13) 3.75(5) min (5/2)+ 922.36 MeV
108Ru 107.91017(12) 4.55(5) min 0+ 921.11 MeV
109Ru 108.91320(7) 34.5(10) s (5/2+)# 929.18 MeV
110Ru 109.91414(6) 11.6(6) s 0+ 937.25 MeV
111Ru 110.91770(8) 2.12(7) s (5/2+) 945.33 MeV
112Ru 111.91897(8) 1.75(7) s 0+ 953.40 MeV
113Ru 112.92249(8) 0.80(5) s (5/2+) 952.15 MeV
114Ru 113.92428(25)# 0.53(6) s 0+ 960.23 MeV
115Ru 114.92869(14) 740(80) ms 968.30 MeV
116Ru 115.93081(75)# 400# ms [>300 ns] 0+ 967.05 MeV
117Ru 116.93558(75)# 300# ms [>300 ns] 975.12 MeV
118Ru 117.93782(86)# 200# ms [>300 ns] 0+ 983.20 MeV
119Ru 118.94284(75)# 170# ms [>300 ns] 981.95 MeV
120Ru 119.94531(86)# 80# ms [>300 ns] 0+ 990.02 MeV
87Ru 86.94918(64)# 50# ms [>1.5 μs] 1/2-# 715.29 MeV
88Ru 87.94026(43)# 1.3(3) s [1.2(+3-2) s] 0+ 731.74 MeV
89Ru 88.93611(54)# 1.38(11) s (7/2)(+#) 743.54 MeV
90Ru 89.92989(32)# 11.7(9) s 0+ 758.13 MeV
91Ru 90.92629(63)# 7.9(4) s (9/2+) 769.00 MeV
92Ru 91.92012(32)# 3.65(5) min 0+ 782.66 MeV
93Ru 92.91705(9) 59.7(6) s (9/2)+ 793.52 MeV
94Ru 93.911360(14) 51.8(6) min 0+ 807.18 MeV
95Ru 94.910413(13) 1.643(14) h 5/2+ 816.19 MeV
96Ru 95.907598(8) STABLE 0+ 827.05 MeV
97Ru 96.907555(9) 2.791(4) d 5/2+ 835.12 MeV
98Ru 97.905287(7) STABLE 0+ 845.06 MeV
99Ru 98.9059393(22) STABLE 5/2+ 853.13 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 13

Abundance

Earth - Seawater: 0.0000007 mg/L 14
Earth -  Crust:  0.001 mg/kg = 0.0000001% 14
Earth -  Total:  1.18 ppm 15
Mercury -  Total:  0.91 ppm 15
Venus -  Total:  1.23 ppm 15
Chondrites - Total: 1.5 (relative to 106 atoms of Si) 16

Compounds

Safety Information


Material Safety Data Sheet - ACI Alloys, Inc.

For More Information

External Links:

Sources

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:26-4:27.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(4) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(6) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(12) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(13) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(14) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(15) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(16) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.