   #copyright

Ruthenium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


                44            technetium ← Ruthenium → rhodium
                Fe
                ↑
                Ru
                ↓
                Os

                                  Periodic Table - Extended Periodic Table

                                                                   General
                                    Name, Symbol, Number Ruthenium, Ru, 44
                                         Chemical series transition metals
                                              Group, Period, Block 8, 5, d
                                         Appearance silvery white metallic
                                              Atomic mass 101.07 (2) g/mol
                                     Electron configuration [Kr] 4d^7 5s^1
                                       Electrons per shell 2, 8, 18, 15, 1
                                                       Physical properties
                                      Density (near r.t.) 12.45 g·cm^−3
                                   Liquid density at m.p. 10.65 g·cm^−3
                                                     Melting point 2607  K
                                                    (2334 ° C, 4233 ° F)
                                                      Boiling point 4423 K
                                                    (4150 ° C, 7502 ° F)
                                         Heat of fusion 38.59 kJ·mol^−1
                                   Heat of vaporization 591.6 kJ·mol^−1
                          Heat capacity (25 °C) 24.06 J·mol^−1·K^−1

   CAPTION: Vapor pressure

                                      P/Pa   1    10  100  1 k  10 k 100 k
                                     at T/K 2588 2811 3087 3424 3845 4388

                                                         Atomic properties
                                               Crystal structure hexagonal
                                            Oxidation states 2, 3, 4, 6, 8
                                                     (mildly acidic oxide)
                                     Electronegativity 2.2 (Pauling scale)
                                     Ionization energies 1st: 710.2 kJ/mol
                                                          2nd: 1620 kJ/mol
                                                          3rd: 2747 kJ/mol
                                                      Atomic radius 130 pm
                                              Atomic radius (calc.) 178 pm
                                                    Covalent radius 126 pm
                                                             Miscellaneous
                                  Electrical resistivity (0 °C) 71 nΩ·m
                        Thermal conductivity (300 K) 117 W·m^−1·K^−1
                        Thermal expansion (25 °C) 6.4 µm·m^−1·K^−1
                               Speed of sound (thin rod) (20 °C) 5970 m/s
                                                   Young's modulus 447 GPa
                                                     Shear modulus 173 GPa
                                                      Bulk modulus 220 GPa
                                                        Poisson ratio 0.30
                                                         Mohs hardness 6.5
                                                 Brinell hardness 2160 MPa
                                             CAS registry number 7440-18-8
                                                         Selected isotopes

                CAPTION: Main article: Isotopes of ruthenium

                             iso    NA   half-life DM   DE ( MeV)     DP
                            ^96Ru  5.52% Ru is stable with 52 neutrons
                            ^97Ru  syn   2.9 d     ε   -            ^97Tc
                                                   γ   0.215, 0.324 -
                            ^98Ru  1.88% Ru is stable with 54 neutrons
                            ^99Ru  12.7% Ru is stable with 55 neutrons
                            ^100Ru 12.6% Ru is stable with 56 neutrons
                            ^101Ru 17.0% Ru is stable with 57 neutrons
                            ^102Ru 31.6% Ru is stable with 58 neutrons
                            ^103Ru syn   39.26 d   β^- 0.226        ^103Rh
                                                   γ   0.497        -
                            ^104Ru 18.7% Ru is stable with 60 neutrons
                            ^106Ru syn   373.59 d  β^- 0.039        ^106Rh

                                                                References

   Ruthenium ( IPA: /ruːˈθiːniəm/) is a chemical element in the periodic
   table that has the symbol Ru and atomic number 44. A rare transition
   metal of the platinum group, ruthenium is found associated with
   platinum ores and used as a catalyst in some platinum alloys.

Notable characteristics

   A polyvalent hard white metal, ruthenium is a member of the platinum
   group, has four crystal modifications and does not tarnish at normal
   temperatures, but does oxidize explosively. Ruthenium dissolves in
   fused alkalis, is not attacked by acids but is attacked by halogens at
   high temperatures. Small amounts of ruthenium can increase the hardness
   of platinum and palladium. The corrosion resistance of titanium is
   increased markedly by the addition of a small amount of ruthenium.

   This metal can be plated either through electrodeposition or by thermal
   decomposition methods. One ruthenium-molybdenum alloy has been found to
   be superconductive at 10.6 K. The oxidation states of ruthenium range
   from +1 to +8, and -2 is known, though oxidation states of +2, +3, and
   +4 are most common.

Applications

   Due to its highly effective ability to harden platinum and palladium,
   ruthenium is used in Pt and Pd alloys to make severe wear-resistant
   electrical contacts. It is sometimes alloyed with gold in jewelry.
     * 0.1% ruthenium is added to titanium to improve its corrosion
       resistance a hundredfold.

   Ruthenium is also a versatile catalyst: Hydrogen sulfide can be split
   by light by using an aqueous suspension of CdS particles loaded with
   ruthenium dioxide. This may be useful in the removal of H[2]S from oil
   refineries and from other industrial processes.

   Organometallic ruthenium carbene and allenylidene complexes have
   recently been found as highly efficient catalysts for olefin metathesis
   with important applications in organic and pharmaceutical chemistry.

   Recently, large metallo-organic complexes of ruthenium have been found
   to exhibit anti-tumor activity and the first of a new group of
   anti-cancer medicine are now in the stage of clinical trials.

   Some ruthenium complexes absorb light throughout the visible spectrum
   and are being actively researched in various, potential, solar energy
   technologies.

   Ruthenium will also be used in some advanced high-temperature
   single-crystal superalloys, with applications including the turbine
   blades in jet engines.

   Ruthenium red, [(NH[3])[5]Ru-O-Ru(NH[3])[4]-O-Ru(NH[3])[5]]^6+, is a
   biological stain used to visualize polyanionic areas of membranes.

   Fountain pen nibs are frequently tipped with alloys containing
   ruthenium. From 1944 onward, the famous Parker 51 fountain pen was
   outfitted with the "RU" nib, a 14K gold nib tipped with 96.2%
   ruthenium, 3.8% iridium.

History

   Ruthenium was discovered and isolated by Karl Klaus in 1844. Klaus
   showed that ruthenium oxide contained a new metal and obtained 6 grams
   of ruthenium from the part of crude platinum that is insoluble in aqua
   regia.

   Jöns Berzelius and Gottfried Osann nearly discovered ruthenium in 1827.
   The men examined residues that were left after dissolving crude
   platinum from the Ural Mountains in aqua regia. Berzelius did not find
   any unusual metals, but Osann thought he found three new metals and
   named one of them ruthenium.

   The name derives from Ruthenia, a latinized name for Russia. Karl Klaus
   called the element in honour of his birthland. He was born in Tartu
   which at that time was part of the Russian Empire.

   It is also possible that Polish chemist Jedrzej Sniadecki isolated
   element 44 (which he called vestium) from platinum ores in 1807.
   However his work was never confirmed and he later withdrew his
   discovery claim.

Occurrence

   This element is generally found in ores with the other platinum group
   metals in the Ural Mountains and in North and South America. Small but
   commercially important quantities are also found in pentlandite
   extracted from Sudbury, Ontario and in pyroxenite deposits in South
   Africa.

   This metal is commercially isolated through a complex chemical process
   in which hydrogen is used to reduce ammonium ruthenium chloride
   yielding a powder. The powder is then consolidated by powder metallurgy
   techniques or by argon- arc welding.

   It is also possible to extract ruthenium from spent nuclear fuel, which
   contains an average of 2 kg of ruthenium per metric ton. Ruthenium
   produced in such a way contains radioactive isotopes, some with a
   half-life of up to 373.59 days. Therefore this ruthenium has to be
   stored at least for 10 years in a secured area to allow it to become
   stable. Fission-derived ruthenium has a specific activity of 8.1 curies
   of radioactivity per gram. Under health physics safety rules any
   isotope that emits more than 1 ci of activity is a hazard; however,
   after 6 years the activity falls to 4.1 ci, after 7 years it is 2.2,
   after 8 years 1.1, after 9 years .55 ci and after 10 years only .27 ci.
   After 20 years the activity falls to 2.702E-4 ci, which is under the
   threshold for low level risk by even the most stringent health physics
   rules.

Compounds

   Ruthenium compounds are often similar in properties to those of osmium
   and exhibit at least eight oxidation states, but the +2, +3, and +4
   states are the most common.

Isotopes

   Naturally occurring ruthenium is composed of seven isotopes. The most
   stable radioisotopes are ^106Ru with a half-life of 373.59 days, ^103Ru
   with a half-life of 39.26 days and ^97Ru with a half-life of 2.9 days.

   Fifteen other radioisotopes have been characterized with atomic weights
   ranging from 89.93 amu (^90Ru) to 114.928 (^115Ru). Most of these have
   half-lifes that are less than five minutes except ^95Ru (half-life:
   1.643 hours) and ^105Ru (half-life: 4.44 hours).

   The primary decay mode before the most abundant isotope, ^102Ru, is
   electron capture and the primary mode after is beta emission. The
   primary decay product before ^102Ru is technetium and the primary mode
   after is rhodium.

Organometallic chemistry

   It is quite easy to form compounds with carbon ruthenium bonds, these
   compounds tend to be darker and react more quickly than the osmium
   compounds. Recently Prof Tony Hill and his co-workers have been making
   compounds of ruthenium in which a boron atom binds to the metal atom.

   The organometallic ruthenium compound that is easiest to make is
   RuHCl(CO)(PPh[3])[3]. This compound has two forms (yellow and pink)
   that are identical once they are dissolved but different in the solid
   state.

   An organometallic compound similar to ruthenocene,
   bis(2,4-dimethylpentadienyl)ruthenium, is readily synthesized in near
   quantitative yields and has applications in vapor-phase deposition of
   metallic ruthenium, as well as in catalysis, including Fischer-Tropsch
   synthesis of transportation fuels.

   Important catalysts based on ruthenium are Grubbs' catalyst and Roper's
   complex.

Precautions

   The compound ruthenium tetroxide, RuO[4], similar to osmium tetroxide,
   is highly toxic and may explode. Ruthenium plays no biological role but
   does strongly stain human skin, may be carcinogenic and bio-accumulates
   in bone.
   Retrieved from " http://en.wikipedia.org/wiki/Ruthenium"
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   with only minor checks and changes (see www.wikipedia.org for details
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