Element 76 · Transition metal
Osmium (Os) — Element 76
Greek osme — smell
Osmium (Os) is a transition metal in Period 6, Group 8 of the periodic table with atomic number 76, standard atomic weight 190.23 u, and ground-state electron configuration [Xe] 4f¹⁴ 5d⁶ 6s². At standard temperature and pressure it is classified as a solid with 8 valence electrons and common oxidation states +4, +8.
Hard alloys, fountain pen tips
What are the atomic properties and physical constants of Osmium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 76
- Standard atomic mass
- 190.23 u
- Chemical family
- Transition metal
- Ground-state configuration
- [Xe] 4f¹⁴ 5d⁶ 6s²
- Electrons per shell
- 2, 8, 18, 32, 14, 2
- Valence electrons
- 8
- Common ion charges / oxidation states
- +4, +8
- Phase at STP
- Solid
- Pauling electronegativity
- 2.20 Pauling
- First ionization energy
- 840 kJ/mol
- Atomic radius
- 185 pm
- Melting point
- 3,033 °C
- Boiling point
- 5,012 °C
- Discovery year
- 1803
- Table coordinate
- Period 6, Group 8
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Osmium’s shells?
A neutral Osmium atom contains 76 electrons distributed across 6 occupied principal energy shells ([Xe] 4f¹⁴ 5d⁶ 6s²). The table below compares Osmium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Os | 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 | 32 e⁻ | 32 e⁻ |
| n = 5 | O | 14 e⁻ | 50 e⁻ |
| n = 6 | P | 2 e⁻ | 72 e⁻ |
Frequently Asked Questions about Osmium (Os)
What is the atomic mass and atomic number of Osmium (Os)?
Osmium (Os) has atomic number Z = 76 (76 protons in its nucleus) and an IUPAC standard atomic weight of 190.23 u. It sits in Period 6, Group 8 and is classified as a transition metal.
What is the ground-state electron configuration of Osmium?
The neutral ground-state electron configuration of Osmium (Z = 76) is [Xe] 4f¹⁴ 5d⁶ 6s². Across its 6 occupied principal shells (n = 1 to n = 6), the electrons per shell are 2, 8, 18, 32, 14, 2, with 8 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Osmium?
Osmium commonly forms +4, +8 oxidation states or ion charges in compounds. Its Pauling electronegativity is 2.20 and its first ionization energy is 840 kJ/mol.
When was Osmium discovered and what is it used for?
Osmium was discovered in 1803 (Greek osme — smell). Hard alloys, fountain pen tips
How does Osmium compare to neighboring elements?
Other transition metal elements: