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Osmium [Os]
CAS-ID: 7440-04-2
An: 76 N: 114
Am: 190.23 (3) g/mol
Group No: 8
Group Name: Precious metal or Platinum group metal
Block: d-block  Period: 6
State: solid at 298 K
Colour: bluish grey Classification: Metallic
Boiling Point: 5285K (5012°C)
Melting Point: 3306K (3033°C)
Superconducting temperature: 0.66K (-272.49°C)
Density: 22.61g/cm3
Discovery Information
Who: Smithson Tenant
When: 1804
Where: England
Name Origin
Greek: osme (odour). A metal with pungent smell.
 "Osmium" in different languages.
Sources
Obtained from the same ores as platinum.
Turkey, with 127,000 tons, has the world's largest known reserve of osmium. Bulgaria also has substantial reserves of about 2500 tons. This transition metal is also found in iridiosmium, a naturally occurring alloy of iridium and osmium, and in platinum-bearing river sands in the Ural Mountains, and North and South America. It also occurs in nickel-bearing ores found in the Sudbury, Ontario region with other platinum group metals. Even though the quantity of platinum metals found in these ores is small, the large volume of nickel ores processed makes commercial recovery possible.
Abundance
 Universe: 0.003 ppm (by weight)
 Sun: 0.002 ppm (by weight)
 Carbonaceous meteorite: 0.67 ppm
 Earth's Crust: 1.8 x 10-3 ppm
Uses
Because of the extreme toxicity of its oxide, osmium is rarely used in its pure state, and is instead often alloyed with other metals that are used in high wear applications. An alloy of 90% platinum and 10% osmium (90/10) is used in surgical implants such as pacemakers and replacement pulmonary valves.
Osmium tetroxide (OsO4) has been used in fingerprint detection and in staining fatty tissue for microscope slides.
Used to tip gold pen points, instrument pivots (such as compass needles and clock bearings), to make electric light filaments. Used for high temperature alloys and pressure bearings.
History
Osmium (Greek osme meaning "a smell") was discovered in 1803 by Smithson Tennant and William Hyde Wollaston in London, England.
Wollaston and Tennant were looking for a way to purify platinum by dissolution of native platinum ore in aqua regia. Large amounts of insoluble black powder remained as a byproduct of this operation.
Wollaston concentrated on the soluble portion and discovered palladium (in 1802) and rhodium (in 1804), while Tennant examined the insoluble residue. In the summer of 1803, Tennant identified two new elements; osmium and iridium. Discovery of the new elements was documented in a letter to the Royal Society on June 21, 1804.
Notes
Osmium in a metallic form is extremely dense, blue white, brittle and lustrous even at high temperatures, but proves to be extremely difficult to make.
Osmium metal has the highest melting point and the lowest vapour pressure of the platinum family.
One cubic metre of osmium would weigh about 22.65 tonnes!
The light bulb manufacturer OSRAM (founded in 1906 when three German companies; Auer-Gesellerschaft, AEG and Siemens and Halske combined their lamp production facilities), derived its name from the elements of OSmium and wolfRAM - OSRAM.
Hazards
Because of the extreme toxicity of its oxide, osmium is rarely used in its pure state, and is instead often alloyed with other metals that are used in high wear applications.
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