Ruthenium (Ru)

Stable isotopes of ruthenium available from ISOFLEX

Isotope Z(p) N(n) Atomic Mass Natural Abundance Enrichment Level Chemical Form
Ru-99 44 55 98.905939 12.7% >96.00% Metal
Ru-100 44 56 99.904219 12.6% >97.00% Metal
Ru-101 44 57 100.905581 17.0% >98.00% Metal
Ru-102 44 58 101.904349 31.6% >98.00% Metal
Ru-104 44 60 103.905429 18.7% ≥99.50 Metal

Request a Quote


Ruthenium was discovered in 1844 by Karl Karlovich Klaus. It takes its name from the Latin name Ruthenia, meaning “Russia.”

Ruthenium is a hard, silvery-white solid with a hexagonal close-packed crystal structure. It is insoluble in water, acids and aqua regia, and it is attacked by alkaline oxidants and by fused alkalis. When heated in air to 500-700 ºC, ruthenium converts to its dioxide, a black crystalline solid of rutile structure. A trioxide of ruthenium is also known and is formed when the metal is heated above 1000 ºC. Above 1100 ºC the metal loses weight because the trioxide partially volatizes.

Halogens react with ruthenium metal at elevated temperatures. The metal is attacked by chlorine water, bromine water or alcoholic solution of iodine at ambient temperatures. When finely divided metal is heated with carbon monoxide under 200 atm pressure, it converts to pentacarbonyl, a colorless liquid that decomposes to diruthenium nonacarbonyl, a yellow crystalline solid. Ruthenium reacts with cyclopentadiene in ether to form a sandwich complex, a yellow crystalline compound, bis(cyslopentadiene) ruthenium(0), also known as ruthenocene.

Ruthenium alloyed to platinum, palladium, titanium or molybdenum has many applications. Because ruthenium is an effective hardening element for platinum and palladium, such alloys have high resistance to corrosion and oxidation and are used to make electrical contacts for resistance to severe wear. Ruthenium-palladium alloys are used in jewelry, decorations and dental work. The addition of 0.1% ruthenium markedly improves the corrosion resistance of titanium. Ruthenium alloys also make tips for fountain pen nibs, instrument pivots and electrical goods.

Properties of Ruthenium

Name Ruthenium
Symbol Ru
Atomic number 44
Atomic weight 101.07
Standard state Solid at 298 °K
CAS Registry ID 7440-18-8
Group in periodic table 8
Group name Precious metal or platinum group metal
Period in periodic table 5
Block in periodic table d-block
Color Silvery white metallic
Classification Metallic
Melting point 2334 °C
Boiling point 3900 °C
Thermal conductivity 117.0 W/(m·K) at 298.2 °K
Electrical resistivity 7.1 µΩ·cm at 0 °C
Electronegativity 2.2 
Specific heat 0.24 kJ/kg K
Heat of vaporization 580 kJ·mol-1 at 3900 °C
Heat of fusion 25.7 kJ·mol-1
Density of liquid 10.65 g/cm3 at 2334 °C
Density of solid 12.37 g/cm3
Electron configuration [Kr]4d75s1
Oxidation states  0, +1, +2, +3, +4, +5, +6, +7, +8
Most stable oxidation states +2, +3, +4
Atomic radius 1.34 Å
Ionic radius Ru8+: 0.36 Å (coordination number 8)


Isotope Supplier: ISOFLEX logo