Si
Silicon
Element 14 · Metalloid
Silicon (Si)
Silicon is a hard, shiny-grey metalloid and the second most abundant element in Earth’s crust. It is the foundation of modern electronics.
- Metalloid
- Period 3
- Group 14
- p-block
- solid at room temperature
Key properties
- Atomic mass
- 28.085
- u
- Electron configuration
- [Ne] 3s2 3p2
- Melting point
- 1,413.9 °C
- 1,687 K
- Boiling point
- 3,264.9 °C
- 3,538 K
- Density
- 2.3296 g/cm³
- Electronegativity
- 1.9
- Pauling
- Atomic radius
- 210 pm
- van der Waals
- 1st ionisation energy
- 8.152 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about silicon
- 01
Sand, quartz and most rocks are made of silicon dioxide and silicates.
- 02
Chip-grade silicon is purified to 99.9999999% or better.
- 03
Silicon Valley in California takes its name from the element.
Applications
What is silicon used for?
- Microchips and transistors
- Solar cells
- Glass and concrete
- Silicone sealants and lubricants
History
Discovery & name origin
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 14
- Atomic mass
- 28.085 u
- Group
- 14
- Period
- 3
- Block
- p-block
- Electron configuration
- [Ne] 3s2 3p2
- Full configuration
- 1s2 2s2 2p6 3s2 3p2
- Electrons per shell
- 2, 8, 4
- Electronegativity (Pauling)
- 1.9
- Electron affinity
- 1.385 eV
- Atomic radius (van der Waals)
- 210 pm
- Stable isotopes
- 3
Oxidation states
Highlighted: common oxidation states (+4, +2, -4).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st786.5
- 2nd1,577.1
- 3rd3,231.6
- 4th4,355.5
- 5th16,091
- 6th19,805
- 7th23,780
- 8th29,287
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 1,687 K · 1,413.9 °C · 2,576.9 °F
- Boiling point
- 3,538 K · 3,264.9 °C · 5,908.7 °F
- Density
- 2.3296 g/cm³
- Molar heat capacity
- 19.789 J/(mol·K)
- Appearance
- Crystalline, reflective with bluish-tinged faces
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Silicon questions
What is Si on the periodic table?
Si is the symbol for silicon, element 14 on the periodic table. It sits in group 14, period 3, in the metalloid category, and has an atomic mass of 28.085.
What is the atomic number of silicon?
Silicon has atomic number 14, so every silicon atom has 14 protons in its nucleus. Its symbol is Si and its atomic mass is 28.085.
Who discovered silicon?
Silicon was discovered by Jöns Jacob Berzelius in 1824 (Sweden). The name comes from Latin silex, “flint”.
What is silicon used for?
Silicon is used for: microchips and transistors; solar cells; glass and concrete; silicone sealants and lubricants.
Is silicon a metal?
No. Silicon is classed as a metalloid, with properties between metals and nonmetals.
What is the electron configuration of silicon?
The electron configuration of silicon is [Ne] 3s2 3p2. Its 14 electrons are arranged in shells as 2, 8, 4.