History Osmium and iridium were discovered at the same time by the

British chemist Smithson Tennant in 1803. Osmium and iridium were identified in the black residue remaining after dissolving platinum ore with aqua regia

Source

Obtained from the same ore with platinum.

Turkey, with 127,000 tonnes, has the world's largest reserves of osmium known.

Bulgaria also has large reserves of about 2500 tons.

These transition metals are also found in iridiosmium, a natural alloy of iridium and osmium, and platinum-bearing river sands in the Ural Mountains, North and South America.

Properties

Group Name: Platinum group

metal Block: Block D Period: 6

solid at 298 K

Colour: blue-gray

Boiling Point: 5285K (5012 ° C)

Melting Point: 3306K (3033 ° C)

Density : 22.61g / cm3

How to get

Metallic osmium is hard, brittle and very difficult to make.

Powdered osmium is easier to make but emits osmium tetroxide (OsO4) when it is exposed to the air. Unfortunately, osmium tetroxide smells bad and is very poisonous. Because of these problems, osmium is primarily used to make very hard alloys. Osmium alloys can be found in ball point pen tips, fountain pen tips, record player needles, electrical contacts and other devices where frictional wear must be minimized.

Compound

Fluorides

Osmium hexafluoride: OsF6

Osmium octafluoride: OsF8

Osmium tetrafluoride: OsF4

Osmium heptafluoride: OsF7

Osmium pentafluoride: [OsF5]4

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Chlorides Osmium trichloride3

Osmium tetrachloride: OsCl4 Osmium pentachloride: OsCl5 Bromides

Osmium tetrabromide: OsBr4

Reaction

Reaction of osmium with air

Osmium is largely immune to atmospheric attack. On heating with oxygen, osmium metal gives the rather volatile (melting point 30°C, boiling point 130°C) osmium (VIII) oxide, OsO4. Apparently, in air, finely divided osmium metal gives off a characteristic smell of OsO4 - bad news given that OsO4 is highly toxic.

Os(s) + 2O2(g) → OsO4(s)

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Reaction of osmium with water

Osmium does not react with water under normal conditions.

Reaction of osmium with the halogens

Osmium reacts with excess of fluorine, F2, at 600°C and 400 atmosphere pressure to form osmium(VII) fluoride, OsF7.

2Os(s) + 7F2(g) → 2OsF7(s) (yellow)

Application

Osmium has only a few uses. It is used to produce very hard alloys for fountain pen tips, instrument pivots, needles and electrical contacts. It is also used in the chemical industry as a catalyst.