1803[2], French chemist Kolez Gotti et al. studied the dissolution of platinum series ores inAqua regiaThe dregs behind.They announced that there were two new metals in the residue that were different from platinum, and they were insoluble in aqua regia.In 1804, Tainar discovered and named them.One of them was named ptenium, later changed to osmium, and the element symbol was Os.Ptenium comes from the Greek word "volatile", and osmium comes from the Greek word "osme", which means "stink", becauseOsmium tetroxideOsOfourIts melting point is only 41 ℃, which is volatile, and the gas has a pungent smell.
Osmium platinum element[2]。Platinum series elementIt exists almost completely in a simple state and is highly dispersed in various ores.Such as original platinum ore, nickel copper sulfide oremagnetiteEtc.Platinum series elements almost invariably coexist to form natural alloys.In ores containing platinum series elements, platinum is usually the main component, while other platinum series elements can only be found after chemical analysis due to their small content.Due to osmiumiridium、palladium、rhodiumandrutheniumBoth of them form ores together with platinum, so they are found in the residue after extracting platinum from platinum ore.The chemical properties of platinum series elements are stable.Apart from platinum and palladium, they are insoluble not only in ordinary acids, but also in aqua regia.Platinum is easily soluble in aqua regia and palladium is also soluble in heatnitric acidMedium.All platinum series elements are strongly formedCoordination compoundThe tendency of.
physical property
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Electronic layout of each layer: 2, 8, 18, 32, 14, 2
Atomic volume: 8.49cmthree/mol
Crust content: 0.0001ppm
Content in the sun: 0.002ppm
Crystal structure: the unit cell is hexagonal unit cell.
Reflective tin white with light blue.Reflectivity: 67.5 (green light), 66 (orange light), 67 (red light).The double reflection of parallel c-axis section is clear.Heterogeneity is weak to medium strong, light pink, red, bronze and gray to dark blue.
Osmium is the highest density among known metal elements, and its density reaches 22.59g/cmthreeThe melting point is 3045 ℃, and the boiling point is above 5027 ℃.Hexagonal dense lattice.Gray blue metal, hard and brittle, can be easily turned into powder when rammed in an iron mortar, osmium powder is blue black, and osmium metal powder can spontaneously ignite.The vapor of osmium tetroxide is highly toxic, which will strongly stimulate people's eye mucosa, and even cause blindness in serious cases.
The chemical formula is OsOtwoThere are two crystal forms (1), which have a molecular weight of 222.20 and are orange brown crystals with a relative density of 11.37 (21.4 ℃). When heated to 500 ℃, 30% of them are converted to osmium tetroxide.Insoluble in water and acids;(2) Molecular weight: 222.20, black powder, relative density: 7.71 (21 ℃), heated to 350~400 ℃ and transformed into reddish brown crystal.Insoluble in water, soluble in dilute hydrochloric acid.It is prepared by heating osmium powder in oxygen or heating and decomposing osmium tetroxide.
Osmium tetroxide
The chemical formula is OsOfour, molecular weight 254.20, CAS No. 20816-12-0, white or yellowish crystal, with chlorine like odor, vapor pressure 0.93kPa (20 ℃), melting point 41.0 ℃, boiling point 130 ℃, slightly soluble in water, ethanol, ethercarbon tetrachlorideAmmonia, density 4.91g/cmthreeIt is mainly used as catalyst, oxidant, chemical reagent, medicine and gauze cover of white hot gas lamp.
Also known as sodium osmium hexachloride, the chemical formula is Natwo[OsClsix], molecular weight 448.90, orange rhombic columnar crystal.Soluble in water and alcohol.It is prepared by adding sodium chloride and reducing agent (such as alcohol) to osmium tetroxide solution.
The chemical formula is OsStwo, molecular weight 254.33, black cubic crystal, thermal decomposition, density 9.47g/cmthree, insoluble in water and alkali, soluble in nitric acid, and directly combined by heating osmium and sulfur.
The chemical formula is OsTetwo, molecular weight is 443.40, it is gray black crystal, melting point is about 600 ℃, it is insoluble in acid, and will decompose when encountering nitric acid.
Iridium osmium ore
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Mineral name: Iridosmine.
Chemical composition: IrOs, mostly containing a little platinum, rhodium, ruthenium, copper, iron, etc.
Identification characteristics: non melting, insoluble in acid.plusSaltpeterIt emits a special odor (OsOfour）If the burnt slag is dissolved in water, there will be black iridium powder precipitation.
Iridium osmium ore picture
Origin and occurrence: in China, it mainly occurs in ultrabasic rock chromite type platinum deposits and placers, and is associated with natural platinum, iridium platinum ore, nickel sulfur palladium platinum oreChrome spinelAnd so on.
Famous places of origin: world famous places of origin include Ural, Chaco in South America, northern Colombia, Oregon, etc.
Name source: named according to its composition.
Crystal form: hexagonal thin plate crystal form.
Crystal system: hexagonal crystal system.
purpose
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Osmium can be used as catalyst in industry[3]。If a little osmium is added into the 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 white dot on the tip of some advanced gold pens is called osmium iridium alloy. The osmium iridium alloy is hard and wear-resistant, and can be used as a bearing for clocks and important instruments with a long service life.
world record
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The most dense metal element in the world:Group VIII elements in the sixth cycle of the periodic table, one of the platinum group metals, with a density of 22.59g/cmthreeIs the metal with the highest density known.(Guinness World Records)
