INORGANIC CHEMISTRY A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site osmium (Os) A bead of high-purity arc-melted osmium. Image copyright: smart-elements.com A hard, silver-gray element in the platinum group; also a transition element. Discovered by Smithson Tennant in London in 1803, osmium is the densest of the elements (twice as dense as lead) and as rare as gold; the chief source is a by-product of smelting nickel. It is slowly oxidized in air. The most common isotope is 192Os (41.0%). Like iridium, osmium is used in producing hard alloys. It is also used to make electrical contacts and pen points. Osmium tetroxide is a colorless or faintly yellowish compound used to stain fats or as a fixative in the preparation of tissues for study by microcope. Osmium tetroxide evaporates readily, the vapor having a toxic action on the eyes, skin, and respiratory tract. atomic number 76 relative atomic mass 190.2 relative density 22.57 melting point 3.045°C (5,513°F) boiling point 5,027°C (9,081°F) Related categories    • ATOMIC AND NUCLEAR PHYSICS    • INORGANIC CHEMISTRY Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP