Symbol: Si
Atomic number: 14
Atomic mass: 28.0855
Group: Non-Metal
CAS-number: 7440-21-3

Physical data
Other info
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Physical data

Electronic data

Shells: 2, 8, 4
Orbitals: [Ne] 3s2 3p2
Electronegativity: 1.8, 1.7
1. Ionization potential: 8.1517 eV
2. Ionization potential: 16.345 eV
3. Ionization potential: 33.492 eV
Oxidation states: 4, -4
Electrical conductivity: 2.52e-12 10^6

Thermal data

Melting point: 1410 °C
Boiling point: 3265 °C
Specific heat: 0.71 J/gK
Heat of fusion: 50.550 kJ/mol
Heat of vaporization: 384.220 kJ/mol
Thermal conductivity: 1.48 W/cmK

Steric data

Atomic radius: 1.46 Å
Ionic radius: 0.26 Å (+4)
Covalent radius: 1.11 Å
Atomic volume: 12.1 cm³/mol
Density (293 K): 2.33 g/cm³
Crystal structure: cubic face centered
cubic face centered


NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
28Si 92.21 27.9769 0 -- --
29Si 4.7 28.9765 1/2 -- --
30Si 3.09 29.9738 0 -- --
31Si 0 30.9753 3/2 2.62h β- View
32Si 0 31.974 0 1.0E02y β- View

Other info

Name origin:Latin: silex, silicus (flint)
Description:Amorphous form is brown powder; crystalline form has gray metallic appearance. Seventh most abundant element in the universe. Second most plentiful element in the earths crust.
Discovered by:Jöns Berzelius
Sources:It makes up a major portion of clay, granite, quartz (SiO2), and sand. Commercial production depends on a reaction between sand (SiO2) and carbon at a temperature of around 2200 °C.
Use(s):It is used in the production of glass as silicon dioxide (SiO2). Silicon carbide (SiC) is one of the hardest substances known and used in polishing. Also the crystalline form is used in semiconductors.