Name: Anonymous 2010-05-28 3:52
#76, Osmium, Os: The name derives from osme, the Greek word for smell. Two previously unkown elements, osmium and iridium, were found together in the insoluble residue of platinum (impure) that was dissolved in aqua regia. A chemical solution of the residue allowed for osmium textroxide, which is very smelly, to be isolated by distilling. Powdered osmium itself smells of osmium tetroxide which forms when the powder is exposed to the air.
Osmium is the densest natural element and can be found alloyed with the similarly dense element iridium in nature, as osmiridium or iridiosmium, with traces of other platinum group metals. Such alloys have commercial use when extreme hardness and durability is required, such as for instrument pivots, electrical contacts, and fountain pen nib tips.
Transmission electron microscopy (TEM), which is the imaging of samples by sending an electron beam through them, is improved by the use of osmium tetroxide staining of biological materials. The stain dissolves in lipids (fats and related chemicals) and gives better contrast to the image as osmium atoms absorb or scatter part of the electron beam much more so than the untreated sample would. Because osmium reduces to elemental form in reaction with the materials and then appears black, the stain also has use in ordinary optical (light) microscopy.
Osmium is useful for the radiometric dating of rocks, specifically rhenium-osmium dating, which is the figuring of age based on ratios of rhenium and osmium isotopes found.
Osmium is the densest natural element and can be found alloyed with the similarly dense element iridium in nature, as osmiridium or iridiosmium, with traces of other platinum group metals. Such alloys have commercial use when extreme hardness and durability is required, such as for instrument pivots, electrical contacts, and fountain pen nib tips.
Transmission electron microscopy (TEM), which is the imaging of samples by sending an electron beam through them, is improved by the use of osmium tetroxide staining of biological materials. The stain dissolves in lipids (fats and related chemicals) and gives better contrast to the image as osmium atoms absorb or scatter part of the electron beam much more so than the untreated sample would. Because osmium reduces to elemental form in reaction with the materials and then appears black, the stain also has use in ordinary optical (light) microscopy.
Osmium is useful for the radiometric dating of rocks, specifically rhenium-osmium dating, which is the figuring of age based on ratios of rhenium and osmium isotopes found.