Osmium (frae Greek osme (ὀσμή) meanin "smell") is a chemical element wi the seembol Os an atomic nummer 76. It is a haird, brickle, blaeish-white transeetion metal in the platinum faimily an is the densest naiturally occurrin element, wi a density o 22.59 g/cm3. It is foond as a trace element in alloys, maistly in platinum ores. Its alloys wi platinum, iridium, an ither platinum group metals are employed in fountain pen tips, electrical contacts, an ither applications whaur extreme durability an hairdness are needit.[3]

Osmium, 76Os
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Osmium
Pronunciation/ˈɒzmiəm/ (OZ-mee-əm)
Appearancesillery, blue cast
Standard atomic weight Ar, std(Os)190.23(3)[1]
Osmium in the periodic cairt
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium
Ru

Os

Hs
rheniumosmiumiridium
Atomic nummer (Z)76
Groupgroup 8
Periodperiod 6
Blockd-block
Element category  Transeetion metal
Electron confeeguration[Xe] 4f14 5d6 6s2
Electrons per shell2, 8, 18, 32, 14, 2
Pheesical properties
Phase at STPsolit
Meltin pynt3306 K ​(3033 °C, ​5491 °F)
Bylin pynt5285 K ​(5012 °C, ​9054 °F)
Density (near r.t.)22.59 g/cm3
when liquid (at m.p.)20 g/cm3
Heat o fusion57.85 kJ/mol
Heat o vapourisation738 kJ/mol
Molar heat capacity24.7 J/(mol·K)
Vapour pressur
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 3160 3423 3751 4148 4638 5256
Atomic properties
Oxidation states−4, −2, −1, 0, +1, +2, +3, +4, +5, +6, +7, +8 (a mildly acidic oxide)
ElectronegativityPauling scale: 2.2
Atomic radiusempirical: 135 pm
Covalent radius144±4 pm
Colour lines in a spectral range
Colour lines in a spectral range
Spectral lines o osmium
Ither properties
Naitural occurrenceprimordial
Creestal structurhexagonal close-packed (hcp)
Hexagonal close packed creestal structur for osmium
Speed o soond thin rod4940 m/s (at 20 °C)
Thermal expansion5.1 µm/(m·K) (at 25 °C)
Thermal conductivity87.6 W/(m·K)
Electrical resistivity81.2 n Ω·m (at 0 °C)
Magnetic orderinparamagnetic[2]
Shear modulus222 GPa
Bulk modulus462 GPa
Poisson ratio0.25
Mohs haurdness7.0
Brinell haurdness3920 MPa
CAS Nummer7440-04-2
History
DiskiverySmithson Tennant (1803)
First isolationSmithson Tennant (1803)
Main isotopes o osmium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct
184Os 0.02% >5.6×1013 y (β+β+) 184W
(α) 180W
185Os syn 93.6 d ε 185Re
186Os 1.59% 2.0×1015 y α 182W
187Os 1.96% - (α) 183W
188Os 13.24% - (α) 184W
189Os 16.15% - (α) 185W
190Os 26.26% - (α) 186W
191Os syn 15.4 d β 191Ir
192Os 40.78% >9.8×1012 y (ββ) 192Pt
(α) 188W
193Os syn 30.11 d β 193Ir
194Os syn 6 y β 194Ir
Decay modes in parentheses are predictit, but hae nae yet been observed
| references

References

eedit
  1. Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
  2. Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
  3. Hammond "Osmium", C. R., p. 4–25 in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.