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Ruthenium (Ru)

Ruthenium is a chemical element of the periodic table with chemical symbol Ru and atomic number 44 with an atomic weight of 101.072 u and is classed as transition metal and is part of group 8 (iron group). Ruthenium is solid at room temperature.

Ruthenium in the periodic table

Atomic number44
Group8 (Iron group)
ClassificationTransition Metal
AppearanceSilvery white metallic
Color Silver
Number of protons44 p+
Number of neutrons57 n0
Number of electrons44 e-
From Wikipedia, the free encyclopediaRuthenium is a chemical element with 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.

Physical properties

Phase at STPSolid
Density12.45 g/cm3
Atomic weight101.072 u

Thermal properties

Melting point2607 K
2333.85 °C
4232.93 °F
Boiling point4423 K
4149.85 °C
7501.73 °F
Heat of vaporization567.77 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)2.2
Electron affinity100.96 kJ/mol
Oxidation states−4, −2, 0, +1, +2, +3, +4, +5, +6, +7, +8
(a mildly acidic oxide)
Ionization energies
  1. 710.2 kJ/mol
  2. 1620 kJ/mol
  3. 2747 kJ/mol

Electron configuration for ruthenium

Electron configuration
Shorthand configuration
[Kr] 4d7 5s1
Electron configuration
Full configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d7 5s1
Electron configuration chart
Electrons per shell2, 8, 18, 15, 1
Valence electrons 8
Valency electrons 3
Bohr model
RutheniumElectron shell for Ruthenium, created by Injosoft ABRu
Figure: Shell diagram of Ruthenium (Ru) atom.
Orbital Diagram

The history of Ruthenium

Discovery and first isolationKarl Ernst Claus (1844)
Discovery of ruthenium
Though naturally occurring platinum alloys containing all six platinum-group metals were used for a long time by pre-Columbian Americans and known as a material to European chemists from the mid-16th century, not until the mid-18th century was platinum identified as a pure element. That natural platinum contained palladium, rhodium, osmium and iridium was discovered in the first decade of the 19th century. It is possible that the Polish chemist Jędrzej Śniadecki isolated element 44 (which he called "vestium" after the asteroid Vesta discovered shortly before) from South American platinum ores in 1807. He published an announcement of his discovery in 1808. His work was never confirmed, however, and he later withdrew his claim of discovery. Jöns Berzelius and Gottfried Osann nearly discovered ruthenium in 1827. They 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, which he called pluranium, ruthenium, and polinium. This discrepancy led to a long-standing controversy between Berzelius and Osann about the composition of the residues. As Osann was not able to repeat his isolation of ruthenium, he eventually relinquished his claims. In 1844, Karl Ernst Claus, a Russian scientist of Baltic German descent, showed that the compounds prepared by Gottfried Osann contained small amounts of ruthenium, which Claus had discovered the same year. Claus isolated ruthenium from the platinum residues of rouble production while he was working in Kazan University, Kazan. Choosing the name for the new element, Claus stated: "I named the new body, in honour of my Motherland, ruthenium. I had every right to call it by this name because Mr. Osann relinquished his ruthenium and the word does not yet exist in chemistry." In doing so, Claus started a trend that continues to this day - naming an element after a country.


List of unique identifiers for Ruthenium in various chemical registry databases
CAS Number7440-18-8
ChemSpider ID22390
EC number231-127-1
PubChem CID Number23950