Osmium (Os): Atomic number: 76, Atomic mass: 190.2 g.mol -1, Electronegativity: 2.2, Density: 22.5 g.cm-3 at 20°C, Melting point: 3045 °C, Boiling point: 5027 °C, Vanderwaals radius: 0.136 nm, Ionic radius: 0.067 nm (+4), Isotopes: 13, Electronic shell: [ Xe ] 4f14 5d- 6s2, Energy of first ionisation: 838 kJ.mol -1, Standard potential: + 0.85 V (Os2+/ Os ), Discovered by: Smithson Tennant in 1803. Osmium is lustrous, silvery metal, one of the so-called platinum group of metals. It is the densest metal known, althoung only by the narrowest margins. Osmium is uneffected by water and acids, but dissolves with molten alkalis. Osmium powder reacts slowly with the oxygen of the air and gives off detacteble amounts of osmium tetroxide vapour. Applications: The metal is used in a few alloys and in industry as a catalyst. At one time it was to be encountered in the nibs of high-quality fountain pens, compass needles, long-life gramophone needles and clock bearings, thanks to its extreme hardness and corrosion resistance. Osmium in the environment: Osmium is mainly found alloyed with other platinum metals, from which it is recovered commercially. The most important ores are either iridosmine and osmiridium. Iridosmine is a rare mineral found in Russia and in North and South America. Less of 100 Kg are produced each year. There is little demand for the metal, which is difficult to fabricate.

 

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Osmium (Os): Atomic number: 76, Atomic mass: 190.2 g.mol -1, Electronegativity: 2.2, Density: 22.5 g.cm-3 at 20°C, Melting point: 3045 °C, Boiling point: 5027 °C, Vanderwaals radius: 0.136 nm, Ionic radi . . . View Full Definition

Operating System (OS): The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recogni . . . View Full Definition