51SbAntimony121.76 u
Antimony (Sb)
Antimony is a metalloid with atomic number 51, in period 5 and group 15 of the periodic table. Its atomic mass is 121.76 u and its electron configuration is [Kr] 4d¹⁰ 5s² 5p³. Solid at 25 °C.
Key facts
| Atomic number | 51 |
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| Atomic mass | 121.76 u |
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| Category | Metalloid |
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| Period | 5 |
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| Group | 15 |
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| Block | p |
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| Electron configuration | [Kr] 4d¹⁰ 5s² 5p³ |
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| Electrons per shell | 2, 8, 18, 18, 5 |
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| Electronegativity (Pauling) | 2.05 |
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| Oxidation states | −3, −2, −1, +1, +2, +3, +4, +5common in bold |
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| State at 25 °C | Solid |
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| Melting point | 903.78 K630.63 °C |
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| Boiling point | 1860 K1586.85 °C |
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| Density | 6.697 g/cm³ |
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Atomic properties
| First ionization energy | 8.608 eV |
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| Electron affinity | 103.2 kJ/mol |
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| Atomic radius | 159 pm |
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| Covalent radius | 139 pm |
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| Van der Waals radius | 206 pm |
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| Common ions | Sb³⁺, Sb⁵⁺ |
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| Protons, neutrons, electrons | 51, 71, 51 |
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Physical and thermal properties
| Molar volume | 18.19 cm³/mol |
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| Heat of fusion | 19.7 kJ/mol |
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| Heat of vaporization | 67 kJ/mol |
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| Specific heat | 207 J/(kg·K) |
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| Thermal conductivity | 24 W/(m·K) |
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| Thermal expansion | 1.1 × 10⁻⁵ K⁻¹ |
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| Mohs hardness | 3 |
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| Young’s modulus | 55 GPa |
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| Crystal structure | Simple trigonal |
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| Magnetic type | Diamagnetic |
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Identification and history
| CAS number | 7440-36-0 |
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| Latin name | Stibium |
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| Discovered by | Before 800 CE |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 121Sb | 120.903811 | 57.21 % |
| 123Sb | 122.904215 | 42.79 % |
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