Ruthenium (Ru)
Transition metal
Ruthenium is a hard, rare platinum-group metal. Hard-disk drives use a ruthenium layer just a few atoms thick, and its catalysts and electrode coatings quietly support the chemical industry.
Position on the periodic table
Atomic properties
| Atomic number | 44 |
|---|---|
| Atomic mass | 101.072 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d7 |
| Noble gas shorthand | [Kr] 4d7 5s1 |
| Electrons per shell | 2, 8, 18, 15, 1 |
| Valence electrons (outer shell) | 1 |
| Common oxidation states | +3, +4, +8 |
| Electronegativity (Pauling) | 2.2 |
| Covalent radius (approx.) | 146 pm |
| First ionization energy | 710.2 kJ/mol |
| Electron affinity | 101 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 12.45 g/cm³ |
| Melting point | 2333.8 °C (2607 K) |
| Boiling point | 4149.9 °C (4423 K) |
| Appearance | silvery white metallic |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of ruthenium
Ruthenium's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d7, usually shortened to [Kr] 4d7 5s1. Its electrons occupy 5 shells (2, 8, 18, 15, 1), placing it in period 5 of the d-block. Explore it interactively in the electron configuration calculator.
Uses of ruthenium
- Hard-disk data layers
- Electrical contacts and thick-film resistors
- Catalysts for ammonia and fine chemicals
- Hardening platinum jewellery alloys
Biological role: None known; some ruthenium complexes are studied as anticancer drugs.
Occurrence: One of the rarest stable elements, recovered from platinum ores.
Common compounds of ruthenium
RuO2
Ruthenium dioxide
History and discovery
Discovered: 1844 — Karl Ernst Claus. Name origin: From Ruthenia, the Latin name for the lands of Rus (Russia).
Karl Ernst Claus isolated ruthenium in 1844 from Ural platinum ore residues.
Safety notes
The metal is inert; the volatile oxide RuO₄ is hazardous in specialist settings.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Ruthenium
1. What is the chemical symbol of Ruthenium?
2. What is the atomic number of Ruthenium?
3. Which category does Ruthenium belong to?
4. What is the state of Ruthenium at room temperature?
5. Which period of the periodic table is Ruthenium in?
Ruthenium FAQs
What is the atomic number of ruthenium?
Ruthenium's atomic number is 44 — every ruthenium atom has 44 protons in its nucleus.
What is the symbol for ruthenium?
Ru. From Ruthenia, the Latin name for the lands of Rus (Russia).
Is ruthenium a metal, nonmetal, or metalloid?
Ruthenium is classified as a transition metal.
What state is ruthenium at room temperature?
At about 25 °C, ruthenium is a solid. It melts at 2333.8 °C.
What is ruthenium used for?
Key uses include: hard-disk data layers; electrical contacts and thick-film resistors; catalysts for ammonia and fine chemicals.
Related elements
Keep working with this element
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