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Silicon (Si)

Silicon is a chemical element of the periodic table with chemical symbol Si and atomic number 14 with an atomic weight of 28.084 u and is classed as metalloid and is part of group 14 (carbon group). Silicon is solid at room temperature.

Silicon in the periodic table

Atomic number14
Group14 (Carbon group)
AppearanceCrystalline, reflective with bluish-tinged faces
Color Gray
Number of protons14 p+
Number of neutrons14 n0
Number of electrons14 e-
From Wikipedia, the free encyclopediaSilicon is a chemical element with symbol Si and atomic number 14. It is a tetravalent metalloid, more reactive than germanium, the metalloid directly below it in the table. Controversy about silicon's character dates to its discovery.

Physical properties

Phase at STPSolid
Density2.329 g/cm3
Atomic weight28.084 u

Thermal properties

Melting point1687 K
1413.85 °C
2576.93 °F
Boiling point3538 K
3264.85 °C
5908.73 °F
Heat of vaporization359 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)1.9
Electron affinity134.068 kJ/mol
Oxidation states−4, −3, −2, −1, 0, +1, +2, +3, +4
(an amphoteric oxide)
Ionization energies
  1. 786.5 kJ/mol
  2. 1577.1 kJ/mol
  3. 3231.6 kJ/mol
  4. 4355.5 kJ/mol
  5. 16091 kJ/mol
  6. 19805 kJ/mol
  7. 23780 kJ/mol
  8. 29287 kJ/mol
  9. 33878 kJ/mol
  10. 38726 kJ/mol
  11. 45962 kJ/mol
  12. 50502 kJ/mol
  13. 235196 kJ/mol
  14. 257923 kJ/mol

Electron configuration for silicon

Electron configuration
Shorthand configuration
[Ne] 3s2 3p2
Electron configuration
Full configuration
1s2 2s2 2p6 3s2 3p2
Electron configuration chart
Electrons per shell2, 8, 4
Valence electrons 4
Valency electrons 4
Bohr model
SiliconElectron shell for Silicon, created by Injosoft ABSi
Figure: Shell diagram of Silicon (Si) atom.
Orbital Diagram

The history of Silicon

PredictionAntoine Lavoisier (1787)
Discovery and first isolationJöns Jacob Berzelius (1823)
Named byThomas Thomson (chemist) (1817)
Discovery of silicon
In 1787, Antoine Lavoisier suspected that silica might be an oxide of a fundamental chemical element. After an attempt to isolate silicon in 1808, Sir Humphry Davy proposed the name "silicium" for silicon. Gay-Lussac and Thénard are thought to have prepared impure amorphous silicon in 1811, through the heating of recently isolated potassium metal with silicon tetrafluoride, but they did not purify and characterize the product, nor identify it as a new element. Silicon was given its present name in 1817 by Scottish chemist Thomas Thomson. He retained part of Davy's name but added "-on" because he believed that silicon was a nonmetal similar to boron and carbon. In 1824, Jöns Jacob Berzelius prepared amorphous silicon using approximately the same method as Gay-Lussac (reducing potassium fluorosilicate with molten potassium metal), but purifying the product to a brown powder by repeatedly washing it. As a result, he is usually given credit for the element's discovery.


List of unique identifiers for Silicon in various chemical registry databases
CAS Number7440-21-3
ChemSpider ID4574465
EC number231-130-8
PubChem CID Number5461123