Ruthenium (Ru)
transition-metalSolid
Standard Atomic Weight
101.07 uElectron configuration
[Kr] 5s1 4d7Melting point
2333.85 °CBoiling point
4149.85 °CDensity
1.21e+4 kg/m³Oxidation states
−4, −2, +1, +2, +3, +4, +5, +6, +7, +8Electronegativity (Pauling)
2.2Ionization energy (1st)
7.3605 eVDiscovery year
1828Atomic radius
130 pmDetails
Ruthenium is a hard, platinum-group transition metal with atomic number 44. It is rare in the crust and is recovered chiefly with platinum and nickel-copper sulfide ores. Chemically it is notable for a wide range of oxidation states, especially +2, +3, +4, +6, and +8, and for forming many coordination and organometallic compounds. Metallic ruthenium improves hardness and corrosion resistance in some platinum and palladium alloys, while its oxides and complexes are important in catalysis and electrochemistry.
Ruthenium is a hard, white metal and has four crystal modifications. It does not tarnish at room temperatures, but 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 cadmium.
The name derives from the Latin ruthenia for the old name of Russia. It was discovered in a crude platinum ore by the Russian chemist Gottfried Wilhelm Osann in 1828. Osann thought that he had found three new metals in the sample, pluranium, ruthenium, and polinium. In 1844, Russian chemist Karl Karlovich Klaus was able to show that Osann's mistake was due to the impurity of the sample, and Klaus was able to isolate the ruthenium metal.
Ruthenium was discovered by Karl Karlovich Klaus, a Russian chemist, in 1844 while analyzing the residue of a sample of platinum ore obtained from the Ural mountains. Apparently, Jedrzej Sniadecki, a Polish chemist, had produced ruthenium in 1807 but he withdrew his claim of discovery after other scientists failed to replicate his results. Ruthenium tends to occur along with deposits of platinum and is primarily obtained as a byproduct of mining and refining platinum. Ruthenium is also obtained as a byproduct of the nickel mining operation in the Sudbury region of Ontario, Canada.
From the Latin word Ruthenia, Russia. In 1827, Berzelius and Osann 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.
Pure ruthenium is a silvery gray, lustrous metal. It is hard and brittle at ordinary temperatures, has a high melting point, and resists attack by air, water, and many acids. Finely divided metal has a much larger reactive surface than compact metal.
Small additions of ruthenium harden platinum and palladium alloys used for wear-resistant electrical contacts, jewelry alloys, and some laboratory or industrial components. Ruthenium-containing materials are used in thick-film resistors and pastes for electronic circuits. Ruthenium dioxide, RuO₂, is an electrically conducting oxide used in electrochemical electrodes and as a catalyst component. Ruthenium complexes are also used as homogeneous catalysts, including catalysts for olefin metathesis and transfer hydrogenation. The radioisotope ¹⁰⁶Ru has been used in ophthalmic brachytherapy sources.
Ruthenium is primarily used as an alloying agent. Adding 0.1% ruthenium to titanium makes titanium 100 times more resistant to corrosion. Small amounts of ruthenium are added to platinum and palladium to strengthen them. These alloys are used in jewelry and in electrical contacts that must resist wear.
Isotopes in Earth/Planetary Science
100Ru is the product of a rare (and hence very long-lived) nuclear decay process from the double beta decay of 100Mo. A careful measurement of the half-life for this decay, which is 7.1×1018 years, can be used to place an upper limit on the mass of the electron neutrino, which is a neutral and weakly interacting subatomic particle first postulated by Wolfgang Pauli in 1930 [326] M. J. Hornish, L. De Braeckeleer, A. S. Barabash, V. I. Umatov. Phys. Rev. C74, 044314 (2006)..
Ruthenium and molybdenum share many similarities. They both have seven isotopes (96, 98, 99, 100, 101, 102, and 104 for ruthenium and 92, 94, 95, 96, 97, 98, and 100 for molybdenum), and their isotopes are formed by the same nucleosynthesisp-processes, r-processes, and s-processes, namely, p, r, s and r, s only, s and r, s and r, and r, respectively. The molybdenum and ruthenium isotopic composition of most meteorites lie along a mixing line (Fig. IUPAC.44.1). The ruthenium and molybdenum of silicates in the Earth also lie on this line, which supports the hypothesis that the Earth accreted homogeneously. That is, the feeding zone of the Earth did not change substantially over time as both the bulk of the Earth and the late veneer accreted from material having the same ruthenium-molybdenum isotopic reservoir [327] N. Dauphas, A. M. Davis, B. Marty, L. Reisberg. Earth Planet. Sci. Lett.226, 465 (2004)..
Isotopes in Medicine
106Ru plaque brachytherapy has been used for eye preservation and tumor control of uveal (the middle layer of the wall of the eye) melanoma [333] L. Tarmann, W. Wackernagel, A. Avian, C. Mayer, M. Schneider, P. Winkler, G. Langmann. Br. J. Ophthalmol.99, 1644 (2015).. The half-life of 106Ru is 373 days.
Isotopes Used as a Source of Radioactive Isotope(s)
96Ru is used to produce radioisotopes 94Ru (with a half-life of 52 min) and 95Ru (with half-life of about 1.64 h) via the reactions 96Ru (n, 3n) 94Ru and 96Ru (n, 2n) 95Ru, respectively (Fig. IUPAC.44.2) [334] A. R. Ketring, G. J. Ehrhardt, M. F. Embree, T. T. Tyler, J. A. Gawenis, S. S. Jurisson, H. P. Engelbrecht, C. J. Smith, C. S. Cutler. Alasbimn J.5 (19), (2003)., [335] J. W. Arblaster. Platinum Met. Rev.55, 124 (2011).. 104Ru is used to produce the radioisotope 105Rh (with a half-life of about 35 h) via the reaction 104Ru (p, γ) 105Rh. 105Rh has been used in the treatment of bone pain [334] A. R. Ketring, G. J. Ehrhardt, M. F. Embree, T. T. Tyler, J. A. Gawenis, S. S. Jurisson, H. P. Engelbrecht, C. J. Smith, C. S. Cutler. Alasbimn J.5 (19), (2003)..
Ruthenium chemistry spans many oxidation states, with +2, +3, and +4 common in coordination compounds and oxides. Ruthenium(III) chloride, RuCl₃, is a common precursor for laboratory synthesis, although commercial material may be hydrated or non-stoichiometric. Ruthenium dioxide, RuO₂, is a stable, conductive oxide with rutile-type structure. Ruthenium tetroxide, RuO₄, contains ruthenium in the +8 state and is a volatile, powerful oxidant. Organometallic ruthenium compounds include arene complexes and carbene complexes used in catalysis.
See more information at the Ruthenium compound page.
Bulk ruthenium metal is relatively inert, but dusts and powders can be fire or inhalation hazards in industrial handling. Soluble ruthenium salts and many complexes should be treated as toxic unless specifically characterized. Ruthenium tetroxide, RuO₄, is especially hazardous because it is volatile, strongly oxidizing, and damaging to tissue. Radioactive isotopes such as ¹⁰⁶Ru present isotope-specific radiation and contamination risks, particularly if dispersed as fine particles or volatile species.
Ruthenium occurs naturally at very low concentrations, mainly associated with platinum-group minerals and sulfide ore systems rather than as a major independent mineral resource. In surface environments it is generally immobile as metal or insoluble oxide, but soluble complexes can behave differently under oxidizing or complexing conditions. Anthropogenic releases are normally small and localized, except in special cases involving mining, refining, industrial catalysts, or nuclear fission products.
Ruthenium is produced as a by-product during refining of platinum-group metal concentrates and, to a lesser extent, nickel-copper sulfide ores. Supply is therefore tied to the mining and refining of other metals rather than to primary ruthenium mining. Demand is modest compared with platinum, palladium, and rhodium, but specialized uses in electronics, catalysts, electrochemical materials, and alloys can require high purity. Recycling occurs from some spent catalysts, electronic materials, and precious-metal alloys, although recovery depends strongly on concentration and process economics.
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 in the Sudbury, Ontario nickel-mining region, and in the pyroxinite deposits of South Africa.
Ruthenium is a heavy element formed mainly by neutron-capture nucleosynthesis in earlier generations of stars. It is far less abundant cosmically than iron-group elements, but it is present in meteorites and planetary materials at trace levels. Its association with other platinum-group elements reflects both nucleosynthetic origin and geochemical partitioning into metal-rich and sulfide-rich phases.
- Ruthenium was named from Ruthenia, a historical Latin name associated with parts of Eastern Europe.
- It is one of the least abundant stable platinum-group metals in Earth’s crust.
- Ruthenium tetroxide, RuO₄, is volatile despite being an oxide of a heavy metal.
- The metal can form a passive oxide surface that contributes to corrosion resistance.
- Some commercial RuCl₃ is not a simple anhydrous compound but a mixture of hydrated chloride species.
- Ruthenium catalysts are central to many well-known olefin metathesis reactions.
Images
Properties
Physical
- Atomic radius (empirical)
- 130 pm Compare Atomic radius (empirical) of all elements →
- Covalent radius
- 146 pm Compare Covalent radius of all elements →
- Van der Waals radius
- 207 pm Compare Van der Waals radius of all elements →
- Metallic radius
- 125 pm Compare Metallic radius of all elements →
- Density
- 1.21 × 104 kg/m³ Compare Density of all elements →
- Molar volume
- 0.0083 L/mol
- Phase at STP
- Solid Compare Phase at STP of all elements →
- Melting point
- 2333.85 °C Compare Melting point of all elements →
- Boiling point
- 4149.85 °C Compare Boiling point of all elements →
- Thermal conductivity
- 117 W/(m·K) Compare Thermal conductivity of all elements →
- Specific heat capacity
- 0.238 J/(g·K) Compare Specific heat capacity of all elements →
- Molar heat capacity
- 24.06 J/(mol·K) Compare Molar heat capacity of all elements →
- Crystal structure
- Hexagonal close-packed Compare Crystal structure of all elements →
Chemical
- Electronegativity (Pauling)
- 2.2 Compare Electronegativity (Pauling) of all elements →
- Electronegativity (Allen)
- 1.54
- Electron affinity
- 1.05 eV
- Ionization energy (1st)
- 7.3605 eV Compare Ionization energy (1st) of all elements →
- Ionization energy (2nd)
- 16.760058 eV Compare Ionization energy (2nd) of all elements →
- Ionization energy (3rd)
- 28.470098 eV Compare Ionization energy (3rd) of all elements →
- Ionization energy (4th)
- 45.000155 eV Compare Ionization energy (4th) of all elements →
- Ionization energy (5th)
- 59.000203 eV Compare Ionization energy (5th) of all elements →
- Oxidation states
- −4, −2, +1, +2, +3, +4, +5, +6, +7, +8 Compare Oxidation states of all elements →
- Valence electrons
- 8 Compare Valence electrons of all elements →
- Electron configuration
- [Kr] 5s1 4d7
Thermodynamic
- Heat of fusion
- 0.24874333 eV Compare Heat of fusion of all elements →
- Heat of vaporization
- 6.166762 eV Compare Heat of vaporization of all elements →
- Heat of sublimation
- 6.736798 eV
- Heat of atomization
- 6.736798 eV
- Atomization enthalpy
- 6.743017 eV
Nuclear
- Protons
- 44 Compare Protons of all elements →
- Neutrons
- 58 Compare Neutrons of all elements →
- Known isotopes
- 41 Compare Known isotopes of all elements →
- Stable isotopes
- 6 Compare Stable isotopes of all elements →
- Most stable isotope
- Ru-102
- Discovery year
- 1828
Abundance
- Abundance (Earth's crust)
- 0.001 mg/kg Compare Abundance (Earth's crust) of all elements →
- Abundance (ocean)
- 7 × 10−7 mg/L Compare Abundance (ocean) of all elements →
Crystal Structure
- Lattice constant a
- 270 pm
Electronic Structure
- Electrons per shell
- 2, 8, 18, 15, 1 Compare Electrons per shell of all elements →
Identifiers
- CAS number
- 7440-18-8 Compare CAS number of all elements →
- Term symbol
- 5F5
- InChI
- InChI=1S/Ru
- InChI Key
- KJTLSVCANCCWHF-UHFFFAOYSA-N
Electron Configuration Measured
Ru: 4d⁷ 5s¹[Kr] 4d⁷ 5s¹1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁷ 5s¹Atomic model
Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.
Schematic atomic model, not to scale.
Atomic Fingerprint
Emission / Absorption Spectrum
Isotope Distribution
| Mass number | Atomic mass (u) | Natural abundance | Half-life |
|---|---|---|---|
| 98 Stable | 97.9052868 ± 0.0000069 | 1.8700% | Stable |
| 99 Stable | 98.9059341 ± 0.0000011 | 12.7600% | Stable |
| 100 Stable | 99.9042143 ± 0.0000011 | 12.6000% | Stable |
| 101 Stable | 100.9055769 ± 0.0000012 | 17.0600% | Stable |
| 102 Stable | 101.9043441 ± 0.0000012 | 31.5500% | Stable |
| 104 Stable | 103.9054275 ± 0.0000028 | 18.6200% | Stable |
Phase / State
Reason: 2308.8 °C below melting point (2333.85 °C)
Schematic, not to scale
Phase transition points
Transition energies
Energy required to melt 1 mol at melting point
Energy required to vaporize 1 mol at boiling point
Energy required to sublime 1 mol at sublimation point
Density
At standard conditions
At standard conditions
Atomic Spectra
Showing 10 of 44. Sorted by ion charge (ascending).
Lines Holdings ?
| Ion | Charge | Total lines | Transition probabilities | Level designations |
|---|---|---|---|---|
| Ru I | 0 | 541 | 11 | 519 |
| Ru II | +1 | 59 | 8 | 59 |
| Ru III | +2 | 93 | 0 | 0 |
Levels Holdings ?
| Ion | Charge | Levels |
|---|---|---|
| Ru I | 0 | 329 |
| Ru II | +1 | 235 |
| Ru III | +2 | 26 |
| Ru IV | +3 | 2 |
| Ru V | +4 | 2 |
| Ru VI | +5 | 2 |
| Ru VII | +6 | 2 |
| Ru VIII | +7 | 2 |
| Ru IX | +8 | 2 |
| Ru X | +9 | 2 |
Ionic Radii
| Charge | Coordination | Spin | Radius |
|---|---|---|---|
| +3 | 6 | N/A | 68 pm |
| +4 | 6 | N/A | 62 pm |
| +5 | 6 | N/A | 56.49999999999999 pm |
| +7 | 4 | N/A | 38 pm |
| +8 | 4 | N/A | 36 pm |
Compounds
Isotopes (6)
| Mass number | Atomic mass (u) | Natural abundance | Half-life | Decay mode | |
|---|---|---|---|---|---|
| 98 Stable | 97.9052868 ± 0.0000069 | 1.8700% ± 0.0300% | Stable | stable | |
| 99 Stable | 98.9059341 ± 0.0000011 | 12.7600% ± 0.1400% | Stable | stable | |
| 100 Stable | 99.9042143 ± 0.0000011 | 12.6000% ± 0.0700% | Stable | stable | |
| 101 Stable | 100.9055769 ± 0.0000012 | 17.0600% ± 0.0200% | Stable | stable | |
| 102 Stable | 101.9043441 ± 0.0000012 | 31.5500% ± 0.1400% | Stable | stable | |
| 104 Stable | 103.9054275 ± 0.0000028 | 18.6200% ± 0.2700% | Stable | stable |
Extended Properties
Covalent Radii (Extended)
- Covalent radius (Pyykkö)
- 125 pm
- Covalent radius (Pyykkö, double)
- 114 pm
- Covalent radius (Pyykkö, triple)
- 103 pm
Van der Waals Radii
- Batsanov
- 205 pm
- Alvarez
- 246 pm
- UFF
- 296.3 pm
- MM3
- 234 pm
Atomic & Metallic Radii
- Atomic radius (Rahm)
- 237 pm
- Metallic radius (C12)
- 134 pm
Numbering Scales
- Mendeleev
- 60
- Pettifor
- 63
- Glawe
- 61
Electronegativity Scales
- Ghosh
- 0
- Miedema
- 5
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 3
Polarizability & Dispersion
- Dipole polarizability
- 72 a.u.
- Dipole polarizability (unc.)
- 10 a.u.
- C₆ (Gould–Bučko)
- 809 Ha·Bohr6
Chemical Affinity
- Proton affinity
- 774 kJ/mol
- Gas basicity
- 751.4 kJ/mol
Miedema Parameters
- Miedema molar volume
- 8.2 cm3/mol
- Miedema electron density
- 6
Supply Risk & Economics
- Production concentration
- 60
- Relative supply risk
- 8
- Reserve distribution
- 95
- Political stability (top producer)
- 44
- Political stability (top reserve)
- 44
Phase Transitions & Allotropes
| Melting point | 2606.15 K |
| Boiling point | 4420.15 K |
Oxidation State Categories
Advanced Reference Data
Screening Constants (10)
| n | Orbital | σ |
|---|---|---|
| 1 | s | 0.9077 |
| 2 | p | 4.0492 |
| 2 | s | 11.6202 |
| 3 | d | 14.6411 |
| 3 | p | 16.7789 |
| 3 | s | 16.3988 |
| 4 | d | 31.1872 |
| 4 | p | 27.5652 |
| 4 | s | 26.344 |
| 5 | s | 37.5155 |
Crystal Radii Detail (5)
| Charge | CN | Spin | rcrystal (pm) | Origin |
|---|---|---|---|---|
| 3 | VI | 82 | ||
| 4 | VI | 76 | from r^3 vs V plots, from metallic oxides, | |
| 5 | VI | 70.5 | estimated, from r^3 vs V plots, | |
| 7 | IV | 52 | ||
| 8 | IV | 50 |
Isotope Decay Modes (62)
| Isotope | Mode | Intensity |
|---|---|---|
| 85 | B+ | — |
| 85 | B+p | — |
| 85 | p | — |
| 86 | B+ | — |
| 86 | B+p | — |
| 87 | B+ | — |
| 87 | B+p | — |
| 88 | B+ | 100% |
| 88 | B+p | 3.6% |
| 89 | B+ | 100% |
X‑ray Scattering Factors (615)
| Energy (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 1.51919 |
| 10.1617 | — | 1.51438 |
| 10.3261 | — | 1.51486 |
| 10.4931 | — | 1.54335 |
| 10.6628 | — | 1.57238 |
| 10.8353 | — | 1.60195 |
| 11.0105 | — | 1.63207 |
| 11.1886 | — | 1.66277 |
| 11.3696 | — | 1.7032 |
| 11.5535 | — | 1.79614 |
Additional Data
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
1×10-3 milligrams per kilogram
References (1)
- [5] Ruthenium https://education.jlab.org/itselemental/ele044.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
7×10-7 milligrams per liter
References (1)
- [5] Ruthenium https://education.jlab.org/itselemental/ele044.html
Sources
Sources of this element.
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 in the Sudbury, Ontario nickel-mining region, and in the pyroxinite deposits of South Africa.
References (1)
- [6] Ruthenium https://periodic.lanl.gov/44.shtml
Production
Production of this element (from raw materials or other compounds containing the element).
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.
References (1)
- [6] Ruthenium https://periodic.lanl.gov/44.shtml
References
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
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The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Ruthenium.
The element property data was retrieved from publications.