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Osmium |
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Pronunciation | (OZ-mee-əm) |
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Appearance | sillery, blue cast |
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Standard atomic weight Ar, std(Os) | 7002190230000000000♠190.23(3)[1] |
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Osmium in the periodic cairt |
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Atomic nummer (Z) | 76 |
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Group | group 8 |
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Period | period 6 |
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Block | d-block |
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Element category | Transeetion metal |
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Electron confeeguration | [Xe] 4f14 5d6 6s2 |
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Electrons per shell | 2, 8, 18, 32, 14, 2 |
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Pheesical properties |
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Phase at STP | solit |
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Meltin pynt | 3306 K (3033 °C, 5491 °F) |
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Bylin pynt | 5285 K (5012 °C, 9054 °F) |
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Density (near r.t.) | 22.59 g/cm3 |
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when liquid (at m.p.) | 20 g/cm3 |
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Heat o fusion | 57.85 kJ/mol |
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Heat o vapourisation | 738 kJ/mol |
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Molar heat capacity | 24.7 J/(mol·K) |
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Vapour pressur
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
3160 |
3423 |
3751 |
4148 |
4638 |
5256 |
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Atomic properties |
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Oxidation states | −4, −2, −1, 0, +1, +2, +3, +4, +5, +6, +7, +8 (a mildly acidic oxide) |
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Electronegativity | Pauling scale: 2.2 |
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Atomic radius | empirical: 135 pm |
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Covalent radius | 144±4 pm |
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Spectral lines o osmium |
Ither properties |
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Naitural occurrence | primordial |
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Creestal structur | hexagonal close-packed (hcp) |
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Speed o soond thin rod | 4940 m/s (at 20 °C) |
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Thermal expansion | 5.1 µm/(m·K) (at 25 °C) |
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Thermal conductivity | 87.6 W/(m·K) |
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Electrical resistivity | 81.2 n Ω·m (at 0 °C) |
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Magnetic orderin | paramagnetic[2] |
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Shear modulus | 222 GPa |
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Bulk modulus | 462 GPa |
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Poisson ratio | 0.25 |
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Mohs haurdness | 7.0 |
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Brinell haurdness | 3920 MPa |
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CAS Nummer | 7440-04-2 |
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History |
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Diskivery | Smithson Tennant (1803) |
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First isolation | Smithson Tennant (1803) |
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Main isotopes o osmium |
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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 |
(β−β−) |
192Pt |
(α) |
188W |
193Os |
syn |
30.11 d |
β− |
193Ir |
194Os |
syn |
6 y |
β− |
194Ir |
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Decay modes in parentheses are predictit, but hae nae yet been observed |
| references |