Os
190.230Osmium
Osmiyum
Osmium is a very dense platinum-group transition metal with atomic number 76. It is known for osmium tetroxide, electron microscopy staining, Sharpless dihydroxylation, hard Os-Ir alloys and Re-Os isotope systems.
76
190.23 g/mol
[Xe] 4f¹⁴ 5d⁶ 6s²
2 | 8 | 18 | 32 | 14 | 2
2.2
22.59 g/cm³
3032.8 °C
5011.9 °C
Smithson Tennant
Osmium was discovered in 1803 by Smithson Tennant in the residue left after crude platinum was dissolved in aqua regia. Its name comes from the Greek word osme, meaning smell, because osmium tetroxide has a sharp odor.
Osmium-184
Natural abundance: About 0.02%. Half-life: About 1.1 x 10¹³ years. Extremely long-lived alpha-emitting natural osmium isotope.Osmium-186
Natural abundance: About 1.6%. Half-life: About 2 x 10¹⁵ years. Extremely long-lived alpha-emitting isotope, linked to rhenium-osmium isotope studies.Osmium-187
Natural abundance: About 2.0%. Daughter isotope from rhenium-187 decay in Re-Os dating.Osmium-188
Natural abundance: About 13.2%. Stable isotope of osmium.Osmium-189
Natural abundance: About 16.1%. Stable isotope of osmium.Osmium-190
Natural abundance: About 26.3%. Stable isotope of osmium.Osmium-192
Natural abundance: About 40.8%. Most abundant natural osmium isotope.OsO₄
Osmium TetroxideElectron microscopy stain and alkene dihydroxylation reagent; highly toxic.OsCl₃
Osmium(III) ChloridePrecursor for osmium coordination and organometallic compounds.[Os(bpy)₃]²⁺
Tris(bipyridyl)osmium(II)Photoredox and electrochemical redox marker research compound.- Osmium tetroxide staining of lipids and membranes for electron microscopy
- Osmium tetroxide in alkene dihydroxylation chemistry, including Sharpless methods
- Hard osmium-iridium alloys for wear-resistant tips and contacts
- Re-Os isotope dating and platinum-group element geochemistry
- Specialized organometallic and photoredox research compounds
Osmium has no known essential biological role. Osmium tetroxide is highly toxic and volatile, so it must be handled with strict laboratory controls.
- Osmium is usually cited as the densest naturally occurring element, very close to iridium.
- Osmium tetroxide is useful because it reacts strongly with carbon-carbon double bonds, especially in lipids.
- The name osmium comes from smell, reflecting the odor of volatile OsO₄.
- Osmium-187 helps connect rhenium decay to geologic dating systems.
- Osmium has atomic number 76 and is a platinum-group metal.
- Its electron configuration is [Xe] 4f¹⁴ 5d⁶ 6s².
- Osmium can show high oxidation states, including +8 in OsO₄.
- Remember osmium for very high density and toxic osmium tetroxide.
What is the atomic number of osmium?
The atomic number of osmium is 76.
What is the electron configuration of osmium?
Osmium has the electron configuration [Xe] 4f¹⁴ 5d⁶ 6s².
What is osmium used for?
Osmium is used mainly in specialized forms such as osmium tetroxide for microscopy and synthesis, hard alloys and isotope studies.
Is osmium the densest element?
Osmium is usually listed as the densest naturally occurring element, with iridium extremely close in density.
Why is osmium tetroxide dangerous?
Osmium tetroxide is volatile, highly toxic and can damage eyes and tissues, so it requires careful laboratory handling.
What is osmium tetroxide used for?
Osmium tetroxide is used to stain lipid-rich biological samples for electron microscopy and as a reagent for alkene dihydroxylation.