40ZrZirconium91.224 u
Zirconium (Zr)
Zirconium is a transition metal with atomic number 40, in period 5 and group 4 of the periodic table. Its atomic mass is 91.224 u and its electron configuration is [Kr] 4d² 5s². Solid at 25 °C.
Key facts
| Atomic number | 40 |
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| Atomic mass | 91.224 u |
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| Category | Transition Metal |
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| Period | 5 |
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| Group | 4 |
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| Block | d |
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| Electron configuration | [Kr] 4d² 5s² |
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| Electrons per shell | 2, 8, 18, 10, 2 |
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| Electronegativity (Pauling) | 1.33 |
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| Oxidation states | −2, +1, +2, +3, +4common in bold |
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| State at 25 °C | Solid |
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| Melting point | 2128 K1854.85 °C |
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| Boiling point | 4682 K4408.85 °C |
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| Density | 6.511 g/cm³ |
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Atomic properties
| First ionization energy | 6.634 eV |
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| Electron affinity | 41.1 kJ/mol |
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| Atomic radius | 160 pm |
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| Covalent radius | 175 pm |
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| Van der Waals radius | 186 pm |
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| Common ions | Zr⁴⁺ |
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| Protons, neutrons, electrons | 40, 51, 40 |
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Physical and thermal properties
| Molar volume | 14.02 cm³/mol |
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| Heat of fusion | 21 kJ/mol |
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| Heat of vaporization | 580 kJ/mol |
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| Specific heat | 278 J/(kg·K) |
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| Thermal conductivity | 23 W/(m·K) |
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| Thermal expansion | 5.7 × 10⁻⁶ K⁻¹ |
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| Mohs hardness | 5 |
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| Young’s modulus | 67 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 | 7440-67-7 |
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| Latin name | Zirconium |
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| Discovered by | Martin Klaproth · 1789 |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 90Zr | 89.904699 | 51.45 % |
| 91Zr | 90.90564 | 11.22 % |
| 92Zr | 91.905035 | 17.15 % |
| 94Zr | 93.906313 | 17.38 % |
| 96Zr | 95.908278 | 2.8 % |
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 Zirconium in the app
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Periodic Table