Ruthenium
[Kr] 4d⁷ 5s¹ · 2 · 8 · 18 · 15 · 1
The rarest and cheapest of the platinum metals, named after Russia. Ruthenium is an excellent catalyst and the additive that makes platinum and palladium markedly harder.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
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Atomic properties
- Atomic number
- 44
- Atomic mass
- 101.07 а.е.м.
- Electron configuration
- [Kr] 4d⁷ 5s¹
- Electrons per shell
- 2 · 8 · 18 · 15 · 1
- Block
- d-block
- Group
- Iron group
- Period
- 5
- Electronegativity (Pauling)
- 2.2
- Electronegativity (Allen)
- 1.54
- Atomic radius
- 178 pm
- Covalent radius
- 146 pm
- Van der Waals radius
- 207 pm
- Ionisation energy 1
- 710.2 kJ/mol
- Ionisation energy 2
- 1 620 kJ/mol
- Ionisation energy 3
- 2 747 kJ/mol
- Electron affinity
- 101.3 kJ/mol
- Common oxidation states
- +3, +4
- Oxidation states
- -4, -2, +1, +2, +3, +4, +5, +6, +7, +8
Physical properties
- State at 25 °C
- solid
- Density
- 12.45 g/cm³
- Melting point
- 2 607 K · 2 333.9 °C
- Boiling point
- 4 423 K · 4 149.9 °C
- Speed of sound
- 5 970 m/s
Thermal properties
- Heat of fusion
- 38.59 kJ/mol
- Heat of vaporisation
- 619 kJ/mol
- Specific heat capacity
- 0.238 J/(g·K)
- Thermal conductivity
- 117 W/(m·K)
Mechanical properties
- Young's modulus
- 447 GPa
- Shear modulus
- 173 GPa
- Bulk modulus
- 220 GPa
- Poisson ratio
- 0.3
- Mohs hardness
- 6.5
- Brinell hardness
- 2 160 MPa
Electrical and magnetic properties
- Electrical resistivity
- 71 nΩ·m
- Magnetic ordering
- paramagnetic
- Curie point
- no data
- Néel point
- no data
- Superconducting point
- 0.49 K
Crystal structure
- Crystal structure
- hexagonal close-packed (hcp)
- Lattice constants
- a = 270.59 pm · c = 428.15 pm
Abundance
- In the crust
- 0.001 mg/kg
- In the ocean
- 7·10⁻⁷ mg/L
- In the universe
- 0.4 mg/kg
- In the human body
- 0 mg/kg
Isotopes
| Isotope | Abundance | Half-life | Decay mode |
|---|---|---|---|
| 96Ru | 5.54 % | stable | — |
| 98Ru | 1.87 % | stable | — |
| 99Ru | 12.76 % | stable | — |
| 100Ru | 12.6 % | stable | — |
| 101Ru | 17.06 % | stable | — |
| 102Ru | 31.55 % | stable | — |
| 104Ru | 18.62 % | stable | — |
Ruthenium-106, half-life about a year, is a fission product; its 2017 atmospheric release was detected across Europe and triggered an international investigation.
Discovery
- Year of discovery
- 1844
- Discovered by
- Karl Klaus
- Where
- Kazan, Russia
- Origin of the name
- from Ruthenia, the Latin name for Rus
History
Karl Klaus isolated ruthenium at Kazan University in 1844 from the residues of Ural platinum, naming it after Ruthenia, the Latin for Rus. It is the last of the six platinum metals and the only element discovered in Russia.
Where it occurs
0.001 mg/kg of the crust. It occurs in platinum placers and in the copper-nickel sulfide ores of Norilsk and the Bushveld.
How it is produced
From anode slimes and platinum concentrates through a long separation chain. World output is about 30 tonnes a year.
Role in living things
No biological role. Ruthenium complexes are being studied as anticancer drugs, a potentially less toxic alternative to platinum ones.
Safety
The metal is inert and harmless. Ruthenium tetroxide, RuO₄, is volatile, extremely toxic and explosive.
Uses
- Resistors and contacts in electronics: ruthenium oxide is the basis of thick-film resistors
- Catalysts for ammonia synthesis and olefin metathesis
- A hardening addition to platinum and palladium in jewellery alloys and electrical contacts
- Hard-disk layers and the nibs of expensive fountain pens
Curiosities
- Ruthenium is the only element discovered in Russia and named for it.
- The 2005 Nobel Prize in Chemistry went to olefin metathesis on ruthenium catalysts.
- One atomic per cent of ruthenium raises titanium's corrosion resistance by an order of magnitude.
- Ruthenium is the most affordable platinum metal, usually several times cheaper than platinum.