45RhRhodium102.90549 u
Rhodium (Rh)
Rhodium is a transition metal with atomic number 45, in period 5 and group 9 of the periodic table. Its atomic mass is 102.90549 u and its electron configuration is [Kr] 4d⁸ 5s¹. Solid at 25 °C.
Key facts
| Atomic number | 45 |
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| Atomic mass | 102.90549 u |
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| Category | Transition Metal |
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| Period | 5 |
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| Group | 9 |
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| Block | d |
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| Electron configuration | [Kr] 4d⁸ 5s¹ |
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| Electrons per shell | 2, 8, 18, 16, 1 |
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| Electronegativity (Pauling) | 2.28 |
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| Oxidation states | −3, −1, +1, +2, +3, +4, +5, +6, +7common in bold |
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| State at 25 °C | Solid |
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| Melting point | 2237 K1963.85 °C |
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| Boiling point | 3968 K3694.85 °C |
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| Density | 12.45 g/cm³ |
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Atomic properties
| First ionization energy | 7.459 eV |
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| Electron affinity | 109.7 kJ/mol |
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| Atomic radius | 134 pm |
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| Covalent radius | 142 pm |
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| Van der Waals radius | 195 pm |
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| Common ions | Rh³⁺ |
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| Protons, neutrons, electrons | 45, 58, 45 |
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Physical and thermal properties
| Molar volume | 8.28 cm³/mol |
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| Heat of fusion | 21.7 kJ/mol |
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| Heat of vaporization | 495 kJ/mol |
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| Specific heat | 240 J/(kg·K) |
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| Thermal conductivity | 150 W/(m·K) |
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| Thermal expansion | 8 × 10⁻⁶ K⁻¹ |
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| Mohs hardness | 6 |
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| Young’s modulus | 275 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 | 7440-16-6 |
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| Latin name | Rhodium |
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| Discovered by | William Hyde Wollaston · 1803 |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 103Rh | 102.905494 | 100 % |
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