ruthenium, rhodium, palladium, osmium, iridium, and platinum together make up the platinum group metals (PGM).

Osmium is lustrous, bluish white, extremely hard, and brittle even at high temperatures. It has the highest melting point and lowest vapour pressure of the platinum group. The metal is very difficult to fabricate, but the powder can be sintered in a hydrogen atmosphere at a temperature of 2000°C. The solid metal is not affected by air at room temperature, but the powdered or spongy metal slowly gives off osmium tetroxide, which is a powerful oxidising agent and has a strong smell. The tetroxide is highly toxic, and boils at 130°C (760 mm). Concentrations in air as low as 10-7 g m-3 can cause lung congestion, skin damage, or eye damage.

The industrial extraction of osmium is complex because the metal is found in ores mixed with other metals such as ruthenium, rhodium, palladium, silver, platinum, and gold. Sometimes extraction of the precious metals such as iridium, rhodium, platinum and palladium is the main focus of a partiular industrial operation while in other cases it is a byproduct.

Preliminary treatment of the ore or base metal byproduct is required to remove silver, gold, palladium, and platinum. The residue is melted with sodium bisulphate (NaHSO4) and the resulting mixture extracted with water to give a solution containing rhodium sulphate, Rh2(SO4)3. The insoluble residue contains the osmium. The residue is melted with Na2O2 and extracted into water to extract the ruthenium and osmium salts (including [RuO4]2- and [OsO4(OH)2]2-). The residue contains iridium oxide, IrO2. Reaction of the salt with chlorine gas gives the volatile oxides RuO4 and OsO4. The osmium oxide is dissolved by treatment with alcoholic sodium hydroxide to form Na2[OsO2(OH)4], and the osmium precipiated out as pure OsCl2O2(NH3)4 by treatment with NH4Cl. Evaporation to dryness and burning under hydrogen gas gives pure osmium.

Osmium was discovered in 1803 by Smithson Tennant in the dark coloured residue left when crude platinum is dissolved by aqua regia (a mixture of hydrochloric and nitric acid). This dark residue contains both osmium (named after osme meaning odor) and iridium.

Osmium

Symbol: Os

Number: 76

Element Category: Transition metal

Group: 8

Period: 6

Block: d

Standard Atomic Weight: 190.23 g·mol⁻¹

Density: 22.61 g/cm3

Electron Configuration: 4f¹⁴ 5d⁶ 6s²

Melting point: 3033^o C

 Boiling Point: 5012^o C

Common Uses: tips of fountain pens, instrument pivots, and electrical contacts

Physical Characteristics at Room Temp: Osmium is an extremely dense, blue-gray, hard but brittle metal that remains lustrous even at high temperatures

IT'S ELEMENTARY!!!