77IrIridium192.217 u
Iridium (Ir)
Iridium is a transition metal with atomic number 77, in period 6 and group 9 of the periodic table. Its atomic mass is 192.217 u and its electron configuration is [Xe] 4f¹⁴ 5d⁷ 6s². Solid at 25 °C.
Key facts
| Atomic number | 77 |
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| Atomic mass | 192.217 u |
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| Category | Transition Metal |
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| Period | 6 |
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| Group | 9 |
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| Block | d |
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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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| Electronegativity (Pauling) | 2.2 |
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| Oxidation states | −3, −1, +1, +2, +3, +4, +5, +6, +7, +8, +9common in bold |
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| State at 25 °C | Solid |
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| Melting point | 2719 K2445.85 °C |
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| Boiling point | 4701 K4427.85 °C |
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| Density | 22.56 g/cm³ |
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Atomic properties
| First ionization energy | 8.967 eV |
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| Electron affinity | 151 kJ/mol |
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| Atomic radius | 136 pm |
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| Covalent radius | 141 pm |
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| Van der Waals radius | 202 pm |
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| Common ions | Ir⁴⁺ |
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| Protons, neutrons, electrons | 77, 115, 77 |
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Physical and thermal properties
| Molar volume | 8.52 cm³/mol |
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| Heat of fusion | 26 kJ/mol |
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| Heat of vaporization | 560 kJ/mol |
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| Specific heat | 131 J/(kg·K) |
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| Thermal conductivity | 150 W/(m·K) |
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| Thermal expansion | 6.4 × 10⁻⁶ K⁻¹ |
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| Mohs hardness | 6.5 |
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| Young’s modulus | 528 GPa |
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| Crystal structure | Face-centered cubic |
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| Magnetic type | Paramagnetic |
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Identification and history
| CAS number | 7439-88-5 |
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| Latin name | Iridium |
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| Discovered by | Smithson Tennant · 1803 |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 191Ir | 190.960591 | 37.3 % |
| 193Ir | 192.962924 | 62.7 % |
Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.
A dash (---) means there is no reliable published measurement. The app never makes one up.
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Periodic Table