ElementsWhat is silicon?
Silicon is the second most common element in the Earth's crust, after oxygen. Sand and quartz are silicon joined with oxygen. Pure silicon is a grey, shiny, brittle solid.
What is silicon used for?
Computer chips, solar cells, glass, cement and concrete, and silicones for sealants and cookware.
Where the name comes from
From the Latin word silex, meaning flint.
Key facts
- Symbol
- Si
- Atomic number
- 14
- Atomic mass
- 28.085 u
- Family
- Metalloid
- Period
- 3
- Group
- 14
- Block
- p
- State at room temperature
- Solid
- Melting point
- 1,414 °C (1,687 K, 2,577 °F)
- Boiling point
- 3,265 °C (3,538 K, 5,909 °F)
- Density
- 2.33 g/cm³
- Electrons per shell
- 2, 8, 4
- Electron configuration
- [Ne]3s2 3p2
- Common oxidation states
- +4, +2, -4
- Electronegativity (Pauling)
- 1.9
- First ionisation energy
- 8.152 eV
- Electron affinity
- 1.385 eV
- Atomic radius (van der Waals)
- 210 pm
- Discovered
- 1824
Place in the periodic table
Silicon is element number 14. It sits in period 3 (row 3) of the periodic table, in group 14 (column 14), and belongs to the p-block. Just before it comes aluminium (13), and just after it comes phosphorus (15). In the same column, carbon is above it and germanium is below it. Elements in one column tend to behave alike.
Family: Metalloids.
Physical properties
At room temperature silicon is a solid. It melts at 1,414 °C and boils at 3,265 °C, so it stays liquid over a range of 1,851 degrees. Its density is 2.33 grams per cubic centimetre, so a one-litre block would weigh about 2.33 kilograms. By density it ranks 74th among the 96 elements with a measured value.
Inside the atom
An atom of silicon has 14 protons in its nucleus and, when neutral, 14 electrons around it. The electrons are arranged in 3 shells: 2, 8, 4. The outermost shell holds 4 electrons. Written in full, the electron configuration is [Ne]3s2 3p2.
Its electronegativity on the Pauling scale is 1.9. This number shows how strongly an atom pulls shared electrons towards itself: fluorine, the strongest, is 3.98. Removing one electron from an atom takes 8.152 electronvolts (about 787 kilojoules per mole). One mole of silicon weighs 28.085 grams, so a single gram contains about 2.14 × 1022 atoms.
The ring picture is a simple model that only counts the electrons in each shell. Real atoms do not look like this.
Next steps
- Work out the weight of a compound that contains silicon with the molar mass calculator.
- Compare it with every other element in the sortable list.
- Test yourself with the symbol quiz.
Figures on this page are from PubChem (U.S. National Library of Medicine), as downloaded on 11 November 2026. See About and data sources.