21ScScandium44.955908 u
Scandium (Sc)
Scandium is a transition metal with atomic number 21, in period 4 and group 3 of the periodic table. Its atomic mass is 44.955908 u and its electron configuration is [Ar] 3d¹ 4s². Solid at 25 °C.
Key facts
| Atomic number | 21 |
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| Atomic mass | 44.955908 u |
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| Category | Transition Metal |
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| Period | 4 |
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| Group | 3 |
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| Block | d |
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| Electron configuration | [Ar] 3d¹ 4s² |
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| Electrons per shell | 2, 8, 9, 2 |
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| Electronegativity (Pauling) | 1.36 |
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| Oxidation states | +1, +2, +3common in bold |
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| State at 25 °C | Solid |
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| Melting point | 1814 K1540.85 °C |
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| Boiling point | 3109 K2835.85 °C |
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| Density | 2.985 g/cm³ |
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Atomic properties
| First ionization energy | 6.561 eV |
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| Electron affinity | 18.1 kJ/mol |
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| Atomic radius | 162 pm |
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| Covalent radius | 170 pm |
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| Van der Waals radius | 211 pm |
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| Common ions | Sc³⁺ |
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| Protons, neutrons, electrons | 21, 24, 21 |
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Physical and thermal properties
| Molar volume | 15 cm³/mol |
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| Heat of fusion | 16 kJ/mol |
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| Heat of vaporization | 318 kJ/mol |
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| Specific heat | 567 J/(kg·K) |
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| Thermal conductivity | 16 W/(m·K) |
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| Thermal expansion | 1.02 × 10⁻⁵ K⁻¹ |
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| Mohs hardness | --- |
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| Young’s modulus | 74 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 | 7440-20-2 |
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| Latin name | Scandium |
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| Discovered by | Lars Fredrik Nilson · 1879 |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 45Sc | 44.955907 | 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 Scandium in the app
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Periodic Table