Osmium, 76 Os Osmium Pronunciation (OZ -mee-əm ) Appearance sillery, blue cast Standard atomic weight A r, std (Os) 7002190230000000000♠ 190.23(3)[ 1] Osmium in the periodic cairt
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) 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) Electronegativity Pauling scale: 2.2 Atomic radius empirical: 135 pm Covalent radius 144±4 pm Colour lines in a spectral range Spectral lines o osmiumIther 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 [ 2] 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
Decay modes in parentheses are predictit, but hae nae yet been observed | references
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