Ruthenium
Element 44 · Transition Metal
Ruthenium is a hard, brittle, silvery metal belonging to the platinum group. It resists corrosion remarkably well and keeps its hardness at high temperatures, which makes it valuable in wear-resistant electrical contacts and in the resistive films of chip resistors found in nearly every electronic device. Chemists also prize ruthenium for its versatile catalysis — ruthenium compounds help drive reactions from ammonia production to the metathesis reactions that earned a Nobel Prize. Like its group neighbor iron, it shows a wide range of oxidation states, all the way up to +8 in the volatile compound ruthenium tetroxide.
Key facts
| Atomic number | 44 |
|---|---|
| Atomic weight | 101.07 |
| Category | Transition Metal |
| Group / Period | 8 / 5 |
| Block | d |
| Electron configuration | [Kr] 4d7 5s1 |
| Common oxidation states | +3, +4, +2, +8 |
| State at STP | Solid |
| Electronegativity | 2.2 |
| Atomic radius | 134 pm (empirical) |
| Density | 12.45 g/cm³ |
| Melting point | 2334 °C |
| Boiling point | 4150 °C |
Occurrence
Ruthenium is one of the rarest elements in Earth's crust. It occurs with the other platinum-group metals in ores mined mainly in South Africa and Russia, and is recovered during platinum and nickel refining.
Applications
Electrical contacts and chip resistors
Industrial catalysts
Hardening platinum jewelry alloys
Fountain pen nibs
Common compounds
- Ruthenium dioxide
- Ruthenium tetroxide
- Ruthenium chloride
Ruthenium is named after Ruthenia, the Latin name for the region of Russia where its ore was studied — it was the last of the platinum-group metals to be isolated.
Data source: IUPAC standard atomic weights 2021; NIST physical property data