Osmium, the heaviest element in the world
Osmium is a group VIII element of the periodic table. One of the platinum group (ruthenium, rhodium, palladium, osmium, iridium, platinum) elements. The element symbol is Os, the atomic number is 76, and the atomic weight is 190.2. The content of the crust is 1 × 10-7% (mass), and it is often symbiotic with other elements of the platinum series, such as original platinum ore, nickel pyrite, nickel sulfide ore, gray-iridium osmium ore, osmium-iridium alloy, etc. Osmium is a gray-blue metal with a melting point of 2700°C, a boiling point higher than 5300°C, and a density of 22.48 g/cm3. Hard and brittle. The bulk metal osmium is chemically inactive and stable in air and humid environments. Spongy or powdered osmium will gradually be oxidized to four Chemicalbook osmium oxides at room temperature. Osmium is mainly used as a hardener for platinum group metal alloys to manufacture various wear-resistant and corrosion-resistant cemented carbides. Alloys made of osmium and iridium, rhodium, ruthenium, platinum, etc. can be used to make contacts and plugs of instruments and electrical appliances. Osmium-iridium alloys can be used as pen tips, record player needles, compasses, pivots for instruments, etc. In the valve industry, the ability of the cathode to emit electrons is enhanced by condensing osmium vapor onto the filament of the valve. Osmium tetroxide can be reduced to black osmium dioxide by certain biological substances, so it is sometimes used as a tissue stain in electron microscopy. Osmium tetroxide is also used in organic synthesis. Osmium metal is non-toxic. Osmium tetroxide is highly irritating and toxic, and has serious effects on skin, eyes and upper respiratory tract.
The metal osmium is gray-blue in color and is the only metal known to be less dense than iridium. Osmium atoms have a dense hexagonal crystal structure, which is a very hard metal. It is hard and brittle at high temperature. The HV of 1473K is 2940MPa, which is difficult to process.
Osmium can be used as catalyst in industry. When using osmium as catalyst in ammonia synthesis or hydrogenation reaction, higher conversion can be obtained at a low temperature. If a little osmium is added to platinum, it can be made into a hard and sharp osmium platinum alloy scalpel. Osmium iridium alloy can be made by using osmium and a certain amount of iridium. For example, the silver dot on the tip of some advanced gold pens is osmium iridium alloy. Osmium iridium alloy is hard and wear-resistant, and can be used as the bearing of clocks and important instruments, with a long service life.
Post time: Jul-27-2022