Osmium, 76Os
Osmium
Pronunciation/ˈɒzmiəm/ (OZ-mee-əm)
Appearancesilvery, blue cast
Standard atomic weight Ar°(Os)
Osmium in the periodic table
Atomic number (Z)76
Groupgroup 8
Periodperiod 6
Block  d-block
Electron configuration[Xe] 4f14 5d6 6s2
Electrons per shell2, 8, 18, 32, 14, 2
Physical properties
Phase at STPsolid
Melting point3306 K (3033 °C, 5491 °F)[3]
Boiling point5281 K (5008 °C, 9046 °F)[3]
Density (at 20° C)22.587 g/cm3 [3]
Heat of fusion57.851 kJ/mol[4] (at m.p.)
Heat of vaporization378 kJ/mol
Molar heat capacity24.7 J/(mol·K)[4]
Specific heat capacity129.843 J/(kg·K)[4]
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 3160 3423 3751 4148 4638 5256
Atomic properties
Oxidation statescommon: +4
−2,[5] −1,[6] 0,[7] +1,[5] +2,[5] +3,[5] +5,[5] +6,[5] +7,[5] +8[5]
ElectronegativityPauling scale: 2.2
Ionization energies
  • 1st: 840 kJ/mol
  • 2nd: 1600 kJ/mol
Atomic radiusempirical: 135 pm
Covalent radius144±4 pm
Color lines in a spectral range
Spectral lines of osmium
Other properties
Natural occurrenceprimordial
Crystal structure hexagonal close-packed (hcp) (hP2)
Lattice constants
Hexagonal close packed crystal structure for osmium
a = 273.42 pm
c = 431.99 pm (at 20 °C)[8]
Thermal expansion4.99×10−6/K (at 20 °C)[a]
Thermal conductivity87.6 W/(m⋅K)[9]
Electrical resistivity81.2 nΩ⋅m (at 0 °C)
Magnetic orderingparamagnetic[10]
Molar magnetic susceptibility11×10−6 cm3/mol[10]
Young's modulus556 GPa
Shear modulus222 GPa
Bulk modulus462 GPa
Speed of sound thin rod4940 m/s (at 20 °C)
Poisson ratio0.25
Mohs hardness7.0
Vickers hardness4137 MPa
Brinell hardness3920 MPa
CAS Number7440-04-2
History
Namingafter Greek osme, "a smell", for the smell of the volatile osmium tetroxide
Discovery and first isolationSmithson Tennant (1803)
Isotopes of osmium
Main isotopes[11] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
184Os 0.02% 1.12×1013 y α 180W
185Os synth 92.95 d ε 185Re
186Os 1.59% 2.0×1015 y α 182W
187Os 1.96% stable
188Os 13.2% stable
189Os 16.1% stable
190Os 26.3% stable
191Os synth 14.99 d β 191Ir
192Os 40.8% stable
193Os synth 29.83 h β 193Ir
194Os synth 6.0 y β 194Ir
 Category: Osmium
| references
child table, as reused in {IB-Os}
Main isotopes of osmium
Main isotopes[11] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
184Os 0.02% 1.12×1013 y α 180W
185Os synth 92.95 d ε 185Re
186Os 1.59% 2.0×1015 y α 182W
187Os 1.96% stable
188Os 13.2% stable
189Os 16.1% stable
190Os 26.3% stable
191Os synth 14.99 d β 191Ir
192Os 40.8% stable
193Os synth 29.83 h β 193Ir
194Os synth 6.0 y β 194Ir
Data sets read by {{Infobox element}}
Name and identifiers
Symbol etymology (11 non-trivial)
Top image (caption, alt) caption:
alt:
Pronunciation
Allotropes (overview)
Group (overview)
Period (overview)
Block (overview)
Natural occurrence
Phase at STP
Oxidation states
Spectral lines image
Electron configuration (cmt, ref)
Isotopes
Standard atomic weight
  most stable isotope
Wikidata
Wikidata *
* Not used in {{Infobox element}} (2023-01-01)
See also {{Index of data sets}} · Cat:data sets (45) · (this table: )

Notes

  1. The thermal expansion of Os is anisotropic: the coefficients for each crystal axis (at 20 °C) are: αa = 4.57×10−6/K, αc = 5.85×10−6/K, and αaverage = αV/3 = 4.99×10−6/K.

References

  1. "Standard Atomic Weights: Osmium". CIAAW. 1991.
  2. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. 1 2 3 Rumble, John R.; Bruno, Thomas J.; Doa, Maria J., eds. (2022). "Section 4: Properties of the Elements and Inorganic Compounds". CRC Handbook of Chemistry and Physics: A Ready Reference Book of Chemical and Physical Data (103rd ed.). Boca Raton, FL: CRC Press. p. 40. ISBN 978-1-032-12171-0.
  4. 1 2 3 Rumble, John R.; Bruno, Thomas J.; Doa, Maria J., eds. (2022). "Section 12: Properties of Solids". CRC Handbook of Chemistry and Physics: A Ready Reference Book of Chemical and Physical Data (103rd ed.). Boca Raton, FL: CRC Press. p. 134. ISBN 978-1-032-12171-0.
  5. 1 2 3 4 5 6 7 8 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. doi:10.1016/C2009-0-30414-6. ISBN 978-0-08-037941-8.
  6. Os(–1) occurs in [Os2(CO)8]2–; see Leh Yeh Hsu; Nripendra Bhattacharyya; Sheldon G. Shore (1985). "Binuclear carbonylates [Ru2(CO)8]2– and [Os2(CO)8]2–: syntheses and crystal structures". Organometallics. 4 (8): 1483–1485. doi:10.1021/om00127a041.
  7. Os(0) is known in Os(CO)5; see Rushman, Paul; Van Buuren, Gilbert N.; Shiralian, Mahmoud; Pomeroy, Roland K. (1983). "Properties of the Pentacarbonyls of Ruthenium and Osmium". Organometallics. 2 (5): 693–694. doi:10.1021/om00077a026.
  8. Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
  9. Rumble, John R.; Bruno, Thomas J.; Doa, Maria J. (2022). "Section 12: Properties of Solids". CRC Handbook of Chemistry and Physics: A Ready Reference Book of Chemical and Physical Data (103rd ed.). Boca Raton, FL: CRC Press. p. 134. ISBN 978-1-032-12171-0.
  10. 1 2 Haynes 2011, p. 4.134.
  11. 1 2 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3) 030001. doi:10.1088/1674-1137/abddae.