44RuRuthenium

Ruthenium is a chemical element with the 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 inert to most other chemicals. Russian-born scientist of Baltic-German ancestry Karl Ernst Claus discovered the element in 1844 at Kazan State University and named ruthenium in honor of Russia. 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 chemistry catalyst. A new application of ruthenium is as the capping layer for extreme ultraviolet photomasks. 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.

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Atomic properties

Standard atomic weight101.07 ±0.02
Atomic mass101.072 u

Atomic radii

Radius (empirical)134 pm
Radius (calculated)178 pm
Covalent radius146 ±7 pm

Atomic shell

Electron configurationKr 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

Phasesolid
Density12.37 g·cm−3
Molar volume8.17·10-6 m3·mol−1
Speed of sound5,970 m·s−1

Temperatures

Melting point2,607 K
Boiling point4,423 K
Liquid range1,816 K
Transition temperature0.5 K

Enthalpies

Melting enthalpy25.7 kJ·mol-1
Enthalpy of vaporization580 kJ·mol-1
Binding energy652 kJ·mol-1

Heat and conductivity

Thermal conductivity120 W·m-1·K-1
Expansion coefficient6.4·10-6 K-1

Hardnesses

Mohs hardness6.5
Brinell hardness2,160 NM·m-2

Elastic properties

Young’s modulus447 GPa
Shear modulus173 GPa
Bulk modulus220 GPa
Poisson’s ratio0.3

Electrical properties

Electrical conductivity1.41·107 S·m-1
Resistance7.1·10-8 Ωm

Magnetism

Magnetismparamagnetic
Magnetic susceptibility3.9·10-5 cm3·mol−1 (298 K)

Chemical properties

Basicityslightly acidic
Oxidation state2, 3, 4, 6, 8

Electronegativity

Pauling scale2.2
Allred-Rochow scale1.42
Ghosh-Gupta scale3.336 eV
Nagle scale1.35
Pearson absolute negativity4.5 eV

Other properties

Natural occurrenceprimordial
Crystal structureHexagonal close-packed
Goldschmidt Classificationsiderophile
Superconductorwith transition tempperature (solid body, normal pressure)
Price/kg10,500 ±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
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