65TbTerbium158.925354 u
Terbium (Tb)
Terbium is a lanthanide with atomic number 65, in period 6, in the f-block of the periodic table. Its atomic mass is 158.925354 u and its electron configuration is [Xe] 4f⁹ 6s². Solid at 25 °C.
Key facts
| Atomic number | 65 |
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| Atomic mass | 158.925354 u |
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| Category | Lanthanide |
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| Period | 6 |
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| Group | f-block, no group number |
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| Block | f |
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| Electron configuration | [Xe] 4f⁹ 6s² |
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| Electrons per shell | 2, 8, 18, 27, 8, 2 |
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| Electronegativity (Pauling) | --- |
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| Oxidation states | +1, +2, +3, +4common in bold |
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| State at 25 °C | Solid |
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| Melting point | 1629 K1355.85 °C |
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| Boiling point | 3503 K3229.85 °C |
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| Density | 8.219 g/cm³ |
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Atomic properties
| First ionization energy | 5.864 eV |
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| Electron affinity | 50 kJ/mol |
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| Atomic radius | 180 pm |
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| Covalent radius | 194 pm |
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| Van der Waals radius | 221 pm |
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| Common ions | Tb³⁺ |
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| Protons, neutrons, electrons | 65, 94, 65 |
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Physical and thermal properties
| Molar volume | 19.3 cm³/mol |
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| Heat of fusion | 10.8 kJ/mol |
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| Heat of vaporization | 295 kJ/mol |
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| Specific heat | 182 J/(kg·K) |
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| Thermal conductivity | 11 W/(m·K) |
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| Thermal expansion | 1.03 × 10⁻⁵ K⁻¹ |
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| Mohs hardness | 2.33 |
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| Young’s modulus | 56 GPa |
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| Crystal structure | Simple hexagonal |
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| Magnetic type | Paramagnetic |
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Identification and history
| CAS number | 7440-27-9 |
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| Latin name | Terbium |
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| Discovered by | Carl Gustaf Mosander · 1843 |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 159Tb | 158.925354 | 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.
See Terbium in the app
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Periodic Table