Ruthenium is a chemical element; it has symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is unreactive to most chemicals. Karl Ernst Claus, a Russian scientist of Baltic-German ancestry, discovered the element in 1844 at Kazan State University and named it in honor of Russia, using the Latin name Ruthenia. Ruthenium is usually found as a minor component of platinum ores; the annual production has risen from about 19 tonnes in 2009 to some 35. 5 tonnes in 2017. Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for ruthenium is in platinum alloys and as a chemical catalyst. A new application of ruthenium is as the capping layer for extreme ultraviolet photomasks in semiconductor lithography. Ruthenium 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.
44RuRuthenium
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Atomic properties
| Standard atomic weight | 101.07 ±0.02 |
|---|---|
| Atomic mass | 101.072 u |
Atomic radii
| Radius (empirical) | 134 pm |
|---|---|
| Radius (calculated) | 178 pm |
| Covalent radius | 146 ±7 pm |
Atomic shell
| Electron configuration | Kr 4d7 5s1 |
|---|---|
| Ionization energy | (1st) 7.3605 eV (2nd) 16.76 eV (3rd) 28.47 eV (4th) 45 eV (5th) 59 eV |
| Shell model | Electrons k-shell:2 l-shell:8 m-shell:18 n-shell:15 o-shell:1 |
Physical properties
| Phase | solid |
|---|---|
| Density | 12.37 g·cm−3 |
| Molar volume | 8.17·10-6 m3·mol−1 |
| Speed of sound | 5,970 m·s−1 |
Temperatures
| Melting point | 2,607 K |
|---|---|
| Boiling point | 4,423 K |
| Liquid range | 1,816 K |
| Transition temperature | 0.5 K |
Enthalpies
| Melting enthalpy | 25.7 kJ·mol-1 |
|---|---|
| Enthalpy of vaporization | 580 kJ·mol-1 |
| Binding energy | 652 kJ·mol-1 |
Heat and conductivity
| Thermal conductivity | 120 W·m-1·K-1 |
|---|---|
| Expansion coefficient | 6.4·10-6 K-1 |
Hardnesses
| Mohs hardness | 6.5 |
|---|---|
| Brinell hardness | 2,160 NM·m-2 |
Elastic properties
| Young’s modulus | 447 GPa |
|---|---|
| Shear modulus | 173 GPa |
| Bulk modulus | 220 GPa |
| Poisson’s ratio | 0.3 |
Electrical properties
| Electrical conductivity | 1.41·107 S·m-1 |
|---|---|
| Resistance | 7.1·10-8 Ωm |
Magnetism
| Magnetism | paramagnetic |
|---|---|
| Magnetic susceptibility | 3.9·10-5 cm3·mol−1 (298 K) |
Chemical properties
| Basicity | slightly acidic |
|---|---|
| Oxidation state | 2, 3, 4, 6, 8 |
Electronegativity
| Pauling scale | 2.2 |
|---|---|
| Allred-Rochow scale | 1.42 |
| Ghosh-Gupta scale | 3.336 eV |
| Nagle scale | 1.35 |
| Pearson absolute negativity | 4.5 eV |
Other properties
| Natural occurrence | primordial |
|---|---|
| Crystal structure | Hexagonal close-packed |
| Goldschmidt Classification | siderophile |
| Superconductor | with transition temperature (solid body, normal pressure) |
| Price/kg | 10,500 ±100 USD |
Natural abundances
satellite_alt
Universe
4 ppb ≈ 4.02·1010 M☉
sunny
Sun
5 ppb ≈ 9.94·109 Mt
destruction
Meteorite
830 ppb ≈ 830 mg
public
Earth’s crust
1 ppb ≈ 27.7 Mt
water_drop
Oceans
7·10-4 ppb ≈ 958 t
waves
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