All practice pages/Interatomic theory/Elements
Element 76, a transition metal
The densest element found in nature, named for the smell of its toxic oxide.
Period 6, group 8. The other transition metals are tinted, and every cell opens its own article.
Like other transition metals, osmium loses its outer s electrons, and often some d electrons as well, to form positive ions, and it can form more than one kind.
Among the rarest elements in the crust, found with platinum in ores from South Africa and Russia and in natural osmium-iridium alloys.
Smithson Tennant found it in 1803, together with iridium, in the black residue left after dissolving platinum ore in aqua regia. He named it from the Greek osme, smell, for the sharp odor of its volatile oxide.
Alloyed with iridium, its extreme hardness tipped fountain pen nibs, phonograph needles and instrument pivots. Osmium tetroxide stains fats for electron microscopes and was once used to reveal fingerprints.
Osmium tetroxide is highly toxic and evaporates easily, and its vapor damages the eyes and lungs. Finely powdered osmium slowly forms it in air.