Atomic number 76
Osmium
Transition metal
In the real world
Quick facts
- Atomic mass
- 190.23
- Group
- 8
- Period
- 6
- State (STP)
- solid
- Electronegativity
- 2.20
- Common ox. states
- +4, +8
Properties
Electron configuration
[Xe] 4f¹⁴ 5d⁶ 6s²
- Ionization energy
- 840.0 kJ/mol
- Electron affinity
- 106.1 kJ/mol
- Melting point
- 3306.00 K (3032.8 °C)
- Boiling point
- 5285.00 K (5011.9 °C)
How dangerous is it?
3/5 · Hazardous
The solid metal is dense and fairly inert, but it slowly gives off a toxic vapor that stings the eyes and lungs. That vapor, not the metal, is the real hazard.
- ToxicImmediate
Osmium slowly forms osmium tetroxide, a volatile vapor that attacks the eyes and the lining of the lungs. (the danger is the oxide vapor, not the bulk metal you can hold)
Stored and worked in a fume hood with sealed containers so the vapor cannot build up.
How it bonds
Osmium is the densest stable element (22.59 g/cm³). Most stable +4, with +8 in OsO₄ - a volatile, toxic, and famously useful oxidizer in organic chemistry (it cleaves alkenes to diols).
