Silicon (Si)
Element 14 · Metalloid · atomic mass 28.085 u · group 14, period 3
Electron shells: 2, 8, 4
Silicon is the second most abundant element in the crust and the semiconductor that the entire computing industry rests on. In nature it appears almost entirely as silica and silicates.
The sand on a beach and the processor in your phone are chemically the same starting material.
- Atomic number
- 14
- Atomic mass
- 28.085 u
- Electron configuration
- [Ne] 3s² 3p²
- Group · period · block
- 14 · 3 · p
- Oxidation states
- −4, +2, +4
- Electronegativity
- 1.9 (Pauling)
- Melting point
- 1,414 °C
- Boiling point
- 3,265 °C
- Density
- 2.3296 g/cm³
- State at 20 °C
- Solid
- Appearance
- Blue-grey, lustrous crystalline solid
- Discovered
- Jöns Jacob Berzelius, 1854
14 protons, and 14 electrons when neutral
IUPAC interval [28.084, 28.086]
Carbon group
What Silicon is used for
- Microchips and solar cells
- Glass and ceramics
- Silicone rubbers and sealants
- Alloying agent in steel and aluminium
Atomic structure of Silicon
A neutral silicon atom has 14 protons and 14 electrons. Its most common isotope carries about 14 neutrons, which is where the mass number 28 comes from. Change the neutron count and you have a different isotope of silicon; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 4. In orbital notation that is [Ne] 3s² 3p², leaving 4 valence electrons in the outer shell — the ones that do the chemistry.
3D electron orbitals
See where Silicon's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Silicon sits in the periodic table
Elements on the staircase between metals and non-metals, showing properties of both. Their intermediate conductivity is what makes semiconductors possible.
- Directly above: Carbon — same group, so similar chemistry with a smaller atom.
- Directly below: Germanium — same group, one shell larger.
- One proton lighter: Aluminum.
- One proton heavier: Phosphorus.
Discovery and naming
Silicon was discovered by Jöns Jacob Berzelius in 1854. Its name comes from Latin silex, "flint".
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Silicon?
The standard atomic weight of Silicon is 28.085 u. Because the natural isotope mix varies between sources, IUPAC publishes it as the interval [28.084, 28.086], and 28.085 is the conventional single value to use in calculations.
How many protons, neutrons and electrons does Silicon have?
Silicon has 14 protons, because the atomic number is the proton count and that is what makes an atom Silicon at all. A neutral Silicon atom has the same number of electrons, 14. The neutron count varies by isotope; the most common one has about 14, since 28 − 14 = 14.
What is the electron configuration of Silicon?
The electron configuration of Silicon is [Ne] 3s² 3p². Its electrons are arranged 2, 8, 4 across 3 shells.
Is Silicon a metal?
Not quite. Silicon is a metalloid — it sits on the staircase dividing metals from non-metals and shows properties of both, which is exactly why metalloids matter to the semiconductor industry.
What group and period is Silicon in?
Silicon is in group 14 (the carbon group), period 3, in the p-block. The group is its column and the period is its row.
What is the charge of Silicon?
Silicon most commonly forms a 4+ or 4− ion. It has 4 outer electrons available to lose. Across all its compounds it shows oxidation states of −4, +2, +4.
What is the melting point of Silicon?
Silicon melts at 1,414 °C and boils at 3,265 °C. That puts it in the solids at everyday temperatures.
What is Silicon used for?
Microchips and solar cells, Glass and ceramics, Silicone rubbers and sealants, Alloying agent in steel and aluminium. Silicon is the second most abundant element in the crust and the semiconductor that the entire computing industry rests on.
Who discovered Silicon, and where does its name come from?
Silicon (Si) was discovered by Jöns Jacob Berzelius in 1854. The name comes from Latin silex, "flint".