Ruthenium (Ru)

Ruthenium (symbol Ru) is the chemical element with atomic number 44: a transition metal, solid at 0 °C, with an atomic mass of 101.07 u. Discovered in 1844 (Karl Ernst Claus).

Ruthenium is one of the six rare, precious “platinum group metals.” Very hard and corrosion-proof, it is used mainly in electronics: a layer just a few atoms thick of ruthenium greatly boosted the capacity of hard drives. It bears the Latin name for Russia, Ruthenia.

Key facts

Atomic number: 44
Symbol: Ru
French name: Ruthénium
Atomic mass: 101.07 u
Molar mass: 101.07 g/mol
Family: Transition metals
Position: period 5, group 8, d-block
State at 0 °C: Solid
Melting point: 2,333.9 °C
Boiling point: 4,149.9 °C
Density: 12.45 g/cm³
Electronegativity (Pauling): 2.2
First ionization energy: 710 kJ/mol
Atomic radius: 130 pm
Electron configuration: [Kr] 4d⁷ 5s¹
Abundance in Earth's crust: 0.001 ppm (77th most abundant element)
Indicative price: 11,000 $/kg (order of magnitude)
Radioactive: no
Discovery: 1844, Karl Ernst Claus

Origin of the name

From the Latin Ruthenia, Russia.

What does ruthenium look like?

A very shiny, silvery-white metal, hard but brittle, that does not tarnish in air at room temperature.

Where is ruthenium found?

Extremely rare: about 0.001 ppm of Earth's crust, or one gram per thousand tonnes of rock. It occurs with platinum in a few large deposits, such as the Bushveld Complex in South Africa and Norilsk in Russia.

Natural sources

Laurite
Ruthenarsenite
Platinum ores (Bushveld, Norilsk)

How is ruthenium produced?

It is separated from the other platinum group metals during refining, at the end of a long chain of dissolutions and precipitations. World output is about 30 tonnes a year, mostly in South Africa.

Top producers

South Africa
Russia
Zimbabwe

What is ruthenium used for?

Magnetic layers in hard drives.
Thick-film resistors in electronic circuits.
Wear-resistant electrical contacts.
Fine-chemical catalysts (olefin metathesis).
Hardening alloys for platinum and palladium jewelry.

In everyday life

Computer hard drive
Circuit boards in electronic devices
Hard tip of some fountain pens

Role in living things

No biological role. Some ruthenium complexes are being studied as anticancer drugs.

Hazards of ruthenium

The metal is inert, but ruthenium tetroxide (RuO₄), which is volatile, is toxic and can explode. Radioactive ruthenium-106 is a fission product.

Cosmic origin

Neutron stars: Created when two neutron stars collide — the “forge” of gold.
Dying stars: Made slowly in red giants (stars like the Sun at the end of their lives).

History of ruthenium

In 1828, Gottfried Osann believed he had found new metals in platinum from the Urals, but failed to convince. In 1844, Karl Ernst Claus, a chemist at Kazan University, truly isolated ruthenium from Russian platinum refining residues, and took up the name Osann had proposed in honor of Russia.

Did you know?

In fall 2017, a cloud of radioactive ruthenium-106 was detected across Europe; it almost certainly came from the Urals, but no facility ever admitted to the incident.
Ruthenium was the last of the platinum group metals to be discovered.
Grubbs's ruthenium catalysts contributed to the 2005 Nobel Prize in Chemistry.

Isotopes of ruthenium

Seven stable isotopes. Ruthenium-106 made headlines in 2017, when a radioactive cloud of unknown origin was detected over Europe.

ruthenium-96: 5.54% of natural ruthenium, stable
ruthenium-98: 1.87% of natural ruthenium, stable
ruthenium-99: 12.76% of natural ruthenium, stable
ruthenium-100: 12.6% of natural ruthenium, stable
ruthenium-101: 17.06% of natural ruthenium, stable
ruthenium-102: 31.55% of natural ruthenium, stable
ruthenium-103: radioactive, half-life 39.2 days. Fission product detected after nuclear accidents.
ruthenium-104: 18.62% of natural ruthenium, stable
ruthenium-106: radioactive, half-life 1.02 years. Plaques placed on the eye to treat certain eye tumors.

Related elements

Same family (transition metals): Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Hafnium (Hf), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Platinum (Pt), Gold (Au), Mercury (Hg), Rutherfordium (Rf), Dubnium (Db), Seaborgium (Sg), Bohrium (Bh), Hassium (Hs).

Same column (group 8): Iron (Fe), Osmium (Os), Hassium (Hs).