Osmium

Osmium, ₇₆Os
Osmium
Pronunciation	/ˈɒzmiəm/ (OZ-mee-əm)
Appearance	sillery, blue cast
Standard atomic weight Ar, std(Os)	190.23(3)
Osmium in the periodic cairt
	rhenium ← osmium → iridium
Atomic nummer (Z)	76
Group	group 8
Period	period 6
Block	d-block
Element category	Transeetion metal
Electron confeeguration	[Xe] 4f14 5d6 6s2
Electrons per shell	2, 8, 18, 32, 14, 2
Pheesical properties
Phase at STP	solit
Meltin pynt	3306 K (3033 °C, 5491 °F)
Bylin pynt	5285 K (5012 °C, 9054 °F)
Density (near r.t.)	22.59 g/cm3
when liquid (at m.p.)	20 g/cm3
Heat o fusion	57.85 kJ/mol
Heat o vapourisation	738 kJ/mol
Molar heat capacity	24.7 J/(mol·K)
Atomic properties
Oxidation states	−4, −2, −1, 0, +1, +2, +3, +4, +5, +6, +7, +8 (a mildly acidic oxide)
Electronegativity	Pauling scale: 2.2
Atomic radius	empirical: 135 pm
Covalent radius	144±4 pm
	Colour lines in a spectral rangeSpectral lines o osmium
Ither properties
Naitural occurrence	primordial
Creestal structur	hexagonal close-packed (hcp)
Speed o soond thin rod	4940 m/s (at 20 °C)
Thermal expansion	5.1 µm/(m·K) (at 25 °C)
Thermal conductivity	87.6 W/(m·K)
Electrical resistivity	81.2 n Ω·m (at 0 °C)
Magnetic orderin	paramagnetic
Shear modulus	222 GPa
Bulk modulus	462 GPa
Poisson ratio	0.25
Mohs haurdness	7.0
Brinell haurdness	3920 MPa
CAS Nummer	7440-04-2
History
Diskivery	Smithson Tennant (1803)
First isolation	Smithson Tennant (1803)
Main isotopes o osmium
(α)	180W
(α)	188W
	Decay modes in parentheses are predictit, but hae nae yet been observed
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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 7004225900000000000♠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]

References

↑ 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.
↑ Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
↑ 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.

[CIAAW2013-1] 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.

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