73TaTantalum180.94788 u
Tantalum (Ta)
Tantalum is a transition metal with atomic number 73, in period 6 and group 5 of the periodic table. Its atomic mass is 180.94788 u and its electron configuration is [Xe] 4f¹⁴ 5d³ 6s². Solid at 25 °C.
Key facts
| Atomic number | 73 |
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| Atomic mass | 180.94788 u |
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| Category | Transition Metal |
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| Period | 6 |
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| Group | 5 |
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| Block | d |
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| Electron configuration | [Xe] 4f¹⁴ 5d³ 6s² |
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| Electrons per shell | 2, 8, 18, 32, 11, 2 |
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| Electronegativity (Pauling) | 1.5 |
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| Oxidation states | −3, −1, +1, +2, +3, +4, +5common in bold |
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| State at 25 °C | Solid |
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| Melting point | 3290 K3016.85 °C |
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| Boiling point | 5731 K5457.85 °C |
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| Density | 16.4 g/cm³ |
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Atomic properties
| First ionization energy | 7.55 eV |
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| Electron affinity | 31 kJ/mol |
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| Atomic radius | 149 pm |
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| Covalent radius | 170 pm |
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| Van der Waals radius | 217 pm |
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| Common ions | Ta⁵⁺ |
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| Protons, neutrons, electrons | 73, 108, 73 |
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Physical and thermal properties
| Molar volume | 10.85 cm³/mol |
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| Heat of fusion | 36 kJ/mol |
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| Heat of vaporization | 736 kJ/mol |
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| Specific heat | 140 J/(kg·K) |
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| Thermal conductivity | 57 W/(m·K) |
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| Thermal expansion | 6.3 × 10⁻⁶ K⁻¹ |
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| Mohs hardness | 6.5 |
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| Young’s modulus | 186 GPa |
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| Crystal structure | Body-centered cubic |
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| Magnetic type | Paramagnetic |
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Identification and history
| CAS number | 7440-25-7 |
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| Latin name | Tantalum |
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| Discovered by | Anders Gustaf Ekeberg · 1802 |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 181Ta | 180.947999 | 99.98799 % |
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