14SiSilicon28.085 u
Silicon (Si)
Silicon is a metalloid with atomic number 14, in period 3 and group 14 of the periodic table. Its atomic mass is 28.085 u and its electron configuration is [Ne] 3s² 3p². Solid at 25 °C.
Key facts
| Atomic number | 14 |
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| Atomic mass | 28.085 u |
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| Category | Metalloid |
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| Period | 3 |
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| Group | 14 |
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| Block | p |
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| Electron configuration | [Ne] 3s² 3p² |
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| Electrons per shell | 2, 8, 4 |
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| Electronegativity (Pauling) | 1.9 |
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| Oxidation states | −4, −3, −2, −1, +1, +2, +3, +4common in bold |
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| State at 25 °C | Solid |
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| Melting point | 1687 K1413.85 °C |
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| Boiling point | 3538 K3264.85 °C |
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| Density | 2.33 g/cm³ |
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Atomic properties
| First ionization energy | 8.152 eV |
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| Electron affinity | 133.6 kJ/mol |
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| Atomic radius | 132 pm |
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| Covalent radius | 111 pm |
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| Van der Waals radius | 210 pm |
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| Common ions | Si⁴⁺, Si⁴⁻ |
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| Protons, neutrons, electrons | 14, 14, 14 |
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Physical and thermal properties
| Molar volume | 12.06 cm³/mol |
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| Heat of fusion | 50.2 kJ/mol |
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| Heat of vaporization | 359 kJ/mol |
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| Specific heat | 710 J/(kg·K) |
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| Thermal conductivity | 150 W/(m·K) |
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| Thermal expansion | 2.6 × 10⁻⁶ K⁻¹ |
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| Mohs hardness | 6.5 |
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| Young’s modulus | 47 GPa |
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| Crystal structure | Tetrahedral packing |
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| Magnetic type | Diamagnetic |
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Identification and history
| CAS number | 7440-21-3 |
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| Latin name | Silicium |
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| Discovered by | Jöns Jacob Berzelius · 1824 |
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| Named by | Thomas Thomson · 1817 |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 28Si | 27.976927 | 92.2545 % |
| 29Si | 28.976495 | 4.672 % |
| 30Si | 29.97377 | 3.0735 % |
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