Ruthenium (Ru) - Properties, Applications

Topics Covered

Chemical Properties
Physical Properties
Mechanical Properties
Thermal Properties


Ruthenium is a rare transition metal that belongs to group 8 and period 5 of the periodic table. Like other platinum group metals, ruthenium is inert to most chemical reactions. This element is generally found in ores of other platinum group metals in the Ural Mountains of South and North America. Commercially, it is obtained from pentlandite, a sulfide of nickel and iron.

Naturally occurring ruthenium consists of seven stable isotopes. It reacts with molten alkali and halogens and oxidizes explosively. The metal remains unaffected by air, acids and water. Ruthenium and its compounds are suspected carcinogens, and ruthenium tetraoxide is a highly toxic compound.

Chemical Properties

The chemical properties of ruthenium are provided in the table below.

Chemical Data
CAS number 7440-18-8
Thermal neutron cross section 2.6 barns/atom
Electrode potential 0.45 V
Ionic radius 0.670 Å
Electronegativity 2.2
X-ray absorption edge 0.56 Å

Physical Properties

The following table discusses the physical properties of ruthenium.

Properties Metric Imperial
Density 12.3 g/cm3 0.444 lb/in3
Melting point 2334°C 4233°F
Boiling point 4150°C 7502°F

Mechanical Properties

The mechanical properties of ruthenium are tabulated below.

Properties Metric Imperial
Tensile strength 370 MPa 53700 psi
Modulus of elasticity 414 GPa 60000 ksi
Shear modulus 173 GPa 25092 ksi
Bulk modulus 220 GPa 31908 ksi
Poisson’s ratio 0.3 0.3
Hardness, Brinell 220 220
Hardness, Vickers 220 220
Hardness, Rockwell A 60 60
Hardness, Rockwell B 96 96
Hardness, Rockwell C 18 18

Thermal Properties

The thermal properties of ruthenium are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@20-100°C/68-212°F) 9.6 µm/m°C 5.33 µin/in°F
Thermal conductivity 116 W/mK 805 BTU in/hr.ft².°F


Ruthenium finds use in electronic industry for manufacturing electrical contacts and chip resistors as well as in chemical industry for use as anodes for chlorine production in electrochemical cells.

The metal also serves as a hardener for platinum and palladium and versatile catalyst in removing H2S from oil refineries and other industrial processes. It is also used to produce thin films of pure ruthenium on substrates, which shows promising properties for use in microchips.

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