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Pronunciation | (i-RID-ee-əm) |
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Appearance | silvery white |
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| 192.217(2)[1] |
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Atomic number (Z) | 77 |
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Group | group 9 |
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Period | period 6 |
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Block | d-block |
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Electron configuration | [Xe] 4f14 5d7 6s2 |
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Electrons per shell | 2, 8, 18, 32, 15, 2 |
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Phase at STP | solid |
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Melting point | 2719 K (2446 °C, 4435 °F) |
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Boiling point | 4403 K (4130 °C, 7466 °F) |
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Density (near r.t.) | 22.56 g/cm3 |
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when liquid (at m.p.) | 19 g/cm3 |
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Heat of fusion | 41.12 kJ/mol |
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Heat of vaporization | 564 kJ/mol |
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Molar heat capacity | 25.10 J/(mol·K) |
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Vapor pressure
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
2713 |
2957 |
3252 |
3614 |
4069 |
4659 |
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Oxidation states | −3, −1, 0, +1, +2, +3, +4, +5, +6, +7, +8, +9[2] |
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Electronegativity | Pauling scale: 2.20 |
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Ionization energies | - 1st: 880 kJ/mol
- 2nd: 1600 kJ/mol
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Atomic radius | empirical: 136 pm |
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Covalent radius | 141±6 pm |
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Spectral lines of iridium |
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Natural occurrence | primordial |
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Crystal structure | face-centered cubic (fcc) |
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Speed of sound thin rod | 4825 m/s (at 20 °C) |
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Thermal expansion | 6.4 µm/(m⋅K) |
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Thermal conductivity | 147 W/(m⋅K) |
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Electrical resistivity | 47.1 nΩ⋅m (at 20 °C) |
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Magnetic ordering | paramagnetic[3] |
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Molar magnetic susceptibility | +25.6 × 10−6 cm3/mol (298 K)[4] |
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Young's modulus | 528 GPa |
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Shear modulus | 210 GPa |
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Bulk modulus | 320 GPa |
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Poisson ratio | 0.26 |
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Mohs hardness | 6.5 |
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Vickers hardness | 1760–2200 MPa |
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Brinell hardness | 1670 MPa |
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CAS Number | 7439-88-5 |
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Discovery and first isolation | Smithson Tennant (1803) |
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Main isotopes[5] |
Decay |
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abundance |
half-life (t1/2) |
mode |
product |
188Ir |
synth |
1.73 d |
ε |
188Os |
189Ir |
synth |
13.2 d |
ε |
189Os |
190Ir |
synth |
11.8 d |
ε |
190Os |
191Ir |
37.3% |
stable |
192Ir |
synth |
73.827 d |
β− |
192Pt |
ε |
192Os |
192m2Ir |
synth |
241 y |
IT |
192Ir |
193Ir |
62.7% |
stable |
193mIr |
synth |
10.5 d |
IT |
193Ir |
194Ir |
synth |
19.3 h |
β− |
194Pt |
194m2Ir |
synth |
171 d |
IT |
194Ir |
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Category: Iridium | references |