Ruthenium Element Facts

44 Ru 101.07 Ruthenium General | States | Energies Oxidation & Electrons | Appearance & Characteristics Reactions | Compounds | Radius | Conductivity Abundance & Isotopes 1 gram bead of high-purity ruthenium.(Photo: Tomihahndorf)

General:

Name: Ruthenium	Symbol: Ru
Type: Transition Metal	Atomic weight: 101.07
Density @ 293 K: 12.2 g/cm3	Atomic volume: 8.3 cm3/mol
Discovered: Ruthenium was discovered in 1827 in an impure form by Gottfried W. Osann in residues of crude platinum ores. Karl Klauss isolated the metal in 1844 from the impure oxide. The element's name comes from the Latin word 'Ruthenia', meaning Russia after Osann's homeland.

States

State (s, l, g): solid
Melting point: 2603 K   (2330 oC)	Boiling point: 4423 K   (4150 oC)

Energies

Specific heat capacity: 0.238 J g-1 K-1	Heat of atomization: 652 kJ mol-1
Heat of fusion: 24.0 kJ mol-1	Heat of vaporization : 595.0 kJ mol-1
1st ionization energy: 711.1 kJ mol-1	2nd ionization energy: 1617.1 kJ mol-1
3rd ionization energy: 2746.9 kJ mol-1	Electron affinity: 101 kJ mol-1

Oxidation & Electrons

Shells: 2,8,18,15,1	Electron configuration: [Kr] 4d7 5s1
Minimum oxidation number: -2	Maximum oxidation number: 8
Min. common oxidation no.: 0	Max. common oxidation no.: 4
Electronegativity (Pauling Scale): 2.2	Polarizability volume: 9.6 Å3

Appearance & Characteristics

Structure: hcp: hexagonal close pkd	Color: silvery-white
Hardness: 6.5 mohs
Harmful effects: Ruthenium is a suspected carcinogen and its compounds strongly stain the skin. Ruthenium tetroxide (RuO4) is highly toxic.
Characteristics: Ruthenium is a very rare, hard, lustrous, brittle, silvery-white metal that does not tarnish at room temperature. The metal is unaffected by air, water and acids. It reacts with molten alkali and halogens and can oxidize explosively.
Uses: Small amounts of ruthenium are used to harden platinum and palladium and it can also be alloyed with these metals to make electrical contacts for severe wear resistance. The addition of 0.1% ruthenium improves the corrosion resistance of titanium a hundred times over. Ruthenium has catalytic properties; for example, hydrogen sulfide can be split by light in the presence of an aqueous suspension of cadmium sulfide particles loaded with ruthenium dioxide.

Reactions

Reaction with air: w/ht, ⇒ RuO4	Reaction with 6 M HCl: none
Reaction with 15 M HNO3: none	Reaction with 6 M NaOH:

Compounds

Oxide(s): RuO2, RuO4	Chloride(s): RuCl2, RuCl3
Hydride(s): none

Radius

Atomic radius: 134 pm	Ionic radius (1+ ion): pm
Ionic radius (2+ ion): pm	Ionic radius (3+ ion): 82 pm
Ionic radius (2- ion): pm	Ionic radius (1- ion): pm

Conductivity

Thermal conductivity: 117 W m-1 K-1

Electrical conductivity: 14.9 x 10-6 S m-1

Abundance & Isotopes

Abundance earth's crust: 1 part per billion by weight, 0.2 parts per billion by moles

Abundance solar system: 5 parts per billion by weight, 0.06 part per billion by moles

Cost, pure: $1400 per 100g

Cost, bulk: $ per 100g

Source: Ruthenium is found free in nature often with the other platinum group metals. Commercially, it is obtained from pentlandite (a sulfide of iron and nickel) which contains small quantities of ruthenium. Ruthenium can also be extracted from spent nuclear fuel, however if obtained this way it will contain radioactive isotopes. It has to be stored safely for at least ten years until the radioactive isotopes have decayed.

Isotopes: Ruthenium has 26 isotopes whose half-lives are known, with mass numbers from 90 to 115. Of these 7 are stable: 96Ru, 98Ru, 99Ru, 100Ru, 101Ru, 102Ru, and104Ru. Naturally, the most common isotope is 102Ru with an abundance of 31.6%.