Element 44 · Transition metal
Ruthenium (Ru) — Element 44
Latin Ruthenia — Russia
Ruthenium (Ru) is a transition metal in Period 5, Group 8 of the periodic table with atomic number 44, standard atomic weight 101.07 u, and ground-state electron configuration [Kr] 4d⁷ 5s¹. At standard temperature and pressure it is classified as a solid with 8 valence electrons and common oxidation states +3, +4.
Electronics, catalysts
What are the atomic properties and physical constants of Ruthenium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 44
- Standard atomic mass
- 101.07 u
- Chemical family
- Transition metal
- Ground-state configuration
- [Kr] 4d⁷ 5s¹
- Electrons per shell
- 2, 8, 18, 15, 1
- Valence electrons
- 8
- Common ion charges / oxidation states
- +3, +4
- Phase at STP
- Solid
- Pauling electronegativity
- 2.20 Pauling
- First ionization energy
- 710 kJ/mol
- Atomic radius
- 178 pm
- Melting point
- 2,334 °C
- Boiling point
- 4,150 °C
- Discovery year
- 1844
- Table coordinate
- Period 5, Group 8
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Ruthenium’s shells?
A neutral Ruthenium atom contains 44 electrons distributed across 5 occupied principal energy shells ([Kr] 4d⁷ 5s¹). The table below compares Ruthenium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Ru | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 18 e⁻ | 18 e⁻ |
| n = 4 | N | 15 e⁻ | 32 e⁻ |
| n = 5 | O | 1 e⁻ | 50 e⁻ |
Frequently Asked Questions about Ruthenium (Ru)
What is the atomic mass and atomic number of Ruthenium (Ru)?
Ruthenium (Ru) has atomic number Z = 44 (44 protons in its nucleus) and an IUPAC standard atomic weight of 101.07 u. It sits in Period 5, Group 8 and is classified as a transition metal.
What is the ground-state electron configuration of Ruthenium?
The neutral ground-state electron configuration of Ruthenium (Z = 44) is [Kr] 4d⁷ 5s¹. Across its 5 occupied principal shells (n = 1 to n = 5), the electrons per shell are 2, 8, 18, 15, 1, with 8 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Ruthenium?
Ruthenium commonly forms +3, +4 oxidation states or ion charges in compounds. Its Pauling electronegativity is 2.20 and its first ionization energy is 710 kJ/mol.
When was Ruthenium discovered and what is it used for?
Ruthenium was discovered in 1844 (Latin Ruthenia — Russia). Electronics, catalysts
How does Ruthenium compare to neighboring elements?
Other transition metal elements: