Si 14

Silicon (Si)

metalloid

Period: 3 Group: 14 Block: p

Solid

Standard Atomic Weight

Electron configuration

[Ne] 3s² 3p²

Melting point

1413.85 °C (1687 K)

Boiling point

3264.85 °C (3538 K)

Density

2329.6 kg/m³

Oxidation states

−4, −3, −2, −1, 0, +1, +2, +3, +4

Electronegativity (Pauling)

1.9

Ionization energy (1st)

Discovery year

1824

Atomic radius

110 pm

Details

Name origin Latin: silex, silicus, (flint).

Discovery country Sweden

Discoverers Jöns Berzelius

Silicon is a hard, brittle metalloid in group 14. It is tetravalent in most compounds and forms strong bonds to oxygen, making silicates the dominant minerals of Earth’s crust. Elemental silicon is central to modern electronics because its oxide, silicon dioxide, can be grown as a stable insulating layer. In bulk chemistry it is less reactive than carbon at ordinary temperatures, but it dissolves or reacts under strongly alkaline, oxidizing, or high-temperature conditions.

Crystalline silicon has a metallic luster and grayish color. Silicon is a relatively inert element, but it is attacked by halogens and dilute alkali. Most acids, except hydrofluoric, do not affect it. Elemental silicon transmits more than 95% of all wavelengths of infrared, from 1.3 to 6.y micro-m.

The name derives from the Latin silex and silicis for "flint". Amorphous silicon was discovered by the Swedish chemist Jöns Jacob Berzelius in 1824. Crystalline silicon was first prepared by the French chemist Henri Sainte-Claire Deville in 1854.

Silicon was discovered by Jöns Jacob Berzelius, a Swedish chemist, in 1824 by heating chips of potassium in a silica container and then carefully washing away the residual by-products. Silicon is the seventh most abundant element in the universe and the second most abundant element in the earth's crust. Today, silicon is produced by heating sand (SiO2) with carbon to temperatures approaching 2200°C.

From the Latin. word silex, silicis, flint. In 1800, Davy thought silica to be a compound and not an element; but in 1811, Gay Lussac and Thenard probably prepared impure amorphous silicon by heating potassium with silicon tetrafluoride.

In 1824 Berzelius, generally credited with the discovery, prepared amorphous silicon by the same general method and purified the product by removing the fluosilicates by repeated washings. Deville in 1854 first prepared crystalline silicon, the second allotropic form of the element.

Read about Silicon on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 110 pm

Covalent radius 111 pm

Van der Waals radius 210 pm

Metallic radius 117 pm

Density

Molar volume 0.0121 L/mol

Phase at STP solid

Melting point 1413.85 °C

Boiling point 3264.85 °C

Thermal conductivity 149 W/(m·K)

Specific heat capacity 0.712 J/(g·K)

Molar heat capacity 19.99 J/(mol·K)

Crystal structure diamond

Chemical

Electronegativity (Pauling) 1.9

Electronegativity (Allen) 1.916

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Ionization energy (3rd)

Ionization energy (4th)

Ionization energy (5th)

Oxidation states −4, −3, −2, −1, 0, +1, +2, +3, +4

Valence electrons 4

Electron configuration

Electron configuration (semantic)

Thermodynamic

Heat of fusion 0.52039177 eV

Heat of vaporization 3.720786 eV

Heat of sublimation 4.670778 eV

Heat of atomization 4.670778 eV

Atomization enthalpy

Nuclear

Stable isotopes 3

Discovery year 1824

Abundance

Abundance (Earth's crust) 2.820e+5 mg/kg

Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 543 pm

Electronic Structure

Electrons per shell 2, 8, 4

Identifiers

CAS number 7440-21-3

Term symbol

InChI InChI=1S/Si

InChI Key XUIMIQQOPSSXEZ-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 14

Electrons 14

Charge Neutral

Configuration Si: 3s² 3p²

[Ne] 3s² 3p²

1s² 2s² 2p⁶ 3s² 3p²

Orbital diagram

↑↓

2/2

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑

2/6 2↑

Total electrons: 14 Unpaired: 2

Atomic model

Protons 14

Neutrons 14

Electrons 14

Mass number 28

Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

Emission Visible: 380–750 nm

Isotope Distribution

Mass number	Atomic mass (u)	Natural abundance	Half-life
28 Stable	27.97692653465 ± 0.00000000044	92.2230%	Stable
29 Stable	28.9764946649 ± 0.00000000052	4.6850%	Stable
30 Stable	29.973770136 ± 0.000000023	3.0920%	Stable

Measured

Phase / State

Solid 25 °C (298.15 K)

Reason: 1388.8 °C below melting point (1413.85 °C)

Melting point 1413.85 °C

Boiling point 3264.85 °C

Below melting by 1388.8 °C

0 K Current temperature: 25 °C 6000 K

Phase timeline

Schematic, not to scale

Solid

Liquid

Gas

Melting

Boiling

25°C

Solid

Liquid

Gas

Current

Phase transition points

Melting point Literature

1413.85 °C

Boiling point Literature

3264.85 °C

Current phase Calculated
Solid

Transition energies

Heat of fusion Literature

0.52039177 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

3.720786 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature

4.670778 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature

2329.6 kg/m³

At standard conditions

Current density Calculated

2329.6 kg/m³

At standard conditions

Atomic Spectra

Showing 10 of 14 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
Si I	0	754	639	640
Si II	+1	590	474	474
Si III	+2	1298	1288	1288
Si IV	+3	332	314	314
Si V	+4	151	143	143
Si VI	+5	346	346	346
Si VII	+6	233	233	233
Si VIII	+7	269	269	269
Si IX	+8	366	366	366
Si X	+9	315	315	315

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
Si I	0	542
Si II	+1	151
Si III	+2	189
Si IV	+3	55
Si V	+4	99
Si VI	+5	72
Si VII	+6	65
Si VIII	+7	60
Si IX	+8	67
Si X	+9	55

NIST Levels Holdings →

14 Si 28.085

Silicon — Atomic Orbital Visualizer

[Ne]3s23p2

Energy levels 2 8 4

Oxidation states -4, -3, -2, -1, 0, +1, +2, +3, +4

HOMO 3p n=3 · l=1 · m=-1

Silicon — Atomic Orbital Visualizer Preview

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14 Si 28.085

Silicon — Crystal Structure Visualizer

Face-Centered Cubic · Pearson cF8

Experimental

Pearson cF8

Coord. № 4

Packing 34.000%

Silicon — Crystal Structure Visualizer Preview

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Ionic Radii

Charge	Coordination	Spin	Radius
+4	4	N/A	26 pm
+4	6	N/A	40 pm

Compounds

28.085 u

Si+4

28.085 u

27.977 u

30.975 u

28.976 u

Si+

28.085 u

29.974 u

31.974 u

Si-

28.085 u

Si+2

28.085 u

Si+3

28.085 u

Isotopes (3)

Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
28 Stable	27.97692653465 ± 0.00000000044	92.2230% ± 0.0190%	Stable	stable
29 Stable	28.9764946649 ± 0.00000000052	4.6850% ± 0.0080%	Stable	stable
30 Stable	29.973770136 ± 0.000000023	3.0920% ± 0.0110%	Stable	stable

28 Stable

Atomic mass (u) 27.97692653465 ± 0.00000000044

Natural abundance 92.2230% ± 0.0190%

Half-life Stable

Decay mode

stable

29 Stable

Atomic mass (u) 28.9764946649 ± 0.00000000052

Natural abundance 4.6850% ± 0.0080%

Half-life Stable

Decay mode

stable

30 Stable

Atomic mass (u) 29.973770136 ± 0.000000023

Natural abundance 3.0920% ± 0.0110%

Half-life Stable

Decay mode

stable

Spectral Lines

Showing 50 of 474 Spectral Lines. Only spectral lines with measured intensity are shown by default.

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
504.1024 nm	1000	Si II	emission	3s2.4p 2P* → 3s2.4d 2D	Measured	NIST
505.5984 nm	1000	Si II	emission	3s2.4p 2P* → 3s2.4d 2D	Measured	NIST
634.711 nm	1000	Si II	emission	3s2.4s 2S → 3s2.4p 2P*	Measured	NIST
637.137 nm	1000	Si II	emission	3s2.4s 2S → 3s2.4p 2P*	Measured	NIST
595.756 nm	500	Si II	emission	3s2.4p 2P* → 3s2.5s 2S	Measured	NIST
597.893 nm	500	Si II	emission	3s2.4p 2P* → 3s2.5s 2S	Measured	NIST
390.55231 nm	300	Si I	emission	3s2.3p2 1S → 3s2.3p.4s 1P*	Measured	NIST
594.8541 nm	200	Si I	emission	3s2.3p.4s 1P* → 3s2.3p.5p 1D	Measured	NIST
700.3569 nm	180	Si I	emission	3s2.3p.4p 3D → 3s2.3p.6d 3F*	Measured	NIST
700.588 nm	180	Si I	emission	3s2.3p.4p 3D → 3s2.3p.6d 3F*	Measured	NIST
570.84 nm	160	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3P	Measured	NIST
462.1722 nm	150	Si II	emission	3s2.4d 2D → 3s2.7f 2F*	Measured	NIST
568.4484 nm	120	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3S	Measured	NIST
462.1418 nm	100	Si II	emission	3s2.4d 2D → 3s2.7f 2F*	Measured	NIST
569.0425 nm	100	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3P	Measured	NIST
579.7856 nm	100	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3D	Measured	NIST
667.184 nm	100	Si II	emission	3s.3p.(3P).4s 4P → 3s.3p.(3P*).4p 4D	Measured	NIST
672.1848 nm	100	Si I	emission	3s2.3p.4p 1P → 3s2.3p.6d 1D*	Measured	NIST
564.5613 nm	90	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3P	Measured	NIST
570.1104 nm	90	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3P	Measured	NIST
579.3073 nm	90	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3D	Measured	NIST
479.2324 nm	80	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.(2P*<3/2>).6p<1/2> (3/2,1/2)	Measured	NIST
566.5555 nm	80	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3P	Measured	NIST
697.651 nm	80	Si I	emission	3s2.3p.4p 3D → 3s2.3p.6d 3F*	Measured	NIST
410.29359 nm	70	Si I	emission	3s2.3p2 1S → 3s2.3p.4s 3P*	Measured	NIST
577.2146 nm	70	Si I	emission	3s2.3p.4s 1P* → 3s2.3p.5p 1S	Measured	NIST
578.0384 nm	70	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3D	Measured	NIST
719.355 nm	65	Si I	emission	3s2.3p.4p 3P → 3s2.3p.6d 3D*	Measured	NIST
478.2991 nm	50	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.(2P*<3/2>).6p<1/2> (3/2,1/2)	Measured	NIST
682.983 nm	50	Si II	emission	3s2.5p 2P* → 3s2.6d 2D	Measured	NIST
575.4218 nm	45	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3P	Measured	NIST
633.1956 nm	45	Si I	emission	3s2.3p.4s 1P* → 3s2.3p.5p 1P	Measured	NIST
655.5463 nm	45	Si I	emission	3s2.3p.4p 3D → 3s2.3p.7d 3F*	Measured	NIST
500.6059 nm	40	Si I	emission	3s2.3p.4s 1P* → 3s2.3p.(2P*<3/2>).6p<3/2> (3/2,3/2)	Measured	NIST
479.2213 nm	35	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.(2P*<1/2>).6p<1/2> (1/2,1/2)	Measured	NIST
380.6526 nm	30	Si III	emission	3s.4p 3P* → 3s.4d 3D	Measured	NIST
455.2622 nm	30	Si III	emission	3s.4s 3S → 3s.4p 3P*	Measured	NIST
494.7607 nm	30	Si I	emission	3s2.3p.4s 1P* → 3s2.3p.(2P*<3/2>).6p<3/2> (3/2,3/2)	Measured	NIST
562.222 nm	30	Si I	emission	3s2.3p.4s 3P* → 3s2.3p.5p 3S	Measured	NIST
681.841 nm	30	Si II	emission	3s2.5p 2P* → 3s2.6d 2D	Measured	NIST
456.784 nm	25	Si III	emission	3s.4s 3S → 3s.4p 3P*	Measured	NIST
392.4468 nm	20	Si III	emission	3s.4f 1F* → 3s.5g 1G	Measured	NIST
457.4757 nm	20	Si III	emission	3s.4s 3S → 3s.4p 3P*	Measured	NIST
573.973 nm	20	Si III	emission	3s.4s 1S → 3s.4p 1P*	Measured	NIST
669.94 nm	20	Si II	emission	3s.3p.(3P).4s 4P → 3s.3p.(3P*).4p 4D	Measured	NIST
482.895 nm	18	Si III	emission	3s.4f 3F* → 3s.5g 3G	Measured	NIST
471.6654 nm	16	Si III	emission	3s.4d 1D → 3s.5f 1F*	Measured	NIST
481.9712 nm	16	Si III	emission	3s.4f 3F* → 3s.5g 3G	Measured	NIST
481.3333 nm	15	Si III	emission	3s.4f 3F* → 3s.5g 3G	Measured	NIST
666.503 nm	15	Si II	emission	3s.3p.(3P).4s 4P → 3s.3p.(3P*).4p 4D	Measured	NIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)

Covalent radius (Pyykkö, double)

Covalent radius (Pyykkö, triple)

Covalent radius (Bragg)

Van der Waals Radii

Bondi

Batsanov

Alvarez

UFF

MM3

Dreiding

Atomic & Metallic Radii

Atomic radius (Rahm)

Metallic radius (C12)

Numbering Scales

Mendeleev

Pettifor

Glawe

Electronegativity Scales

Ghosh

Miedema

Gunnarsson–Lundqvist

Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability

Dipole polarizability (unc.)

C₆

C₆ (Gould–Bučko)

Chemical Affinity

Proton affinity

Gas basicity

Miedema Parameters

Miedema molar volume

Miedema electron density

Phase Transitions & Allotropes

Melting point	1687.15 K
Boiling point	3538.15 K

Oxidation State Categories

−1 extended

+1 extended

+3 extended

+4 main

0 extended

+2 extended

−4 main

−3 extended

−2 extended

Advanced Reference Data

Screening Constants (5)

n	Orbital	σ
1	s	0.4255
2	p	4.055
2	s	4.98
3	p	9.7148
3	s	9.0968

Crystal Radii Detail (2)

Charge	CN	Spin	r_crystal (pm)	Origin
4	IV		40
4	VI		54	from r^3 vs V plots,

Isotope Decay Modes (46)

Isotope	Mode	Intensity
22	B+	100%
22	B+p	62%
22	2p	0.7%
23	B+	100%
23	B+p	88%
23	2p	3.6%
24	B+	100%
24	B+p	34.5%
25	B+	100%
25	B+p	35%

X‑ray Scattering Factors (756)

Energy (eV)	f₁	f₂
10	—	3.94851
10.1617	—	3.95531
10.3261	—	3.96212
10.4931	—	3.96894
10.6628	—	3.97577
10.8353	—	3.98262
11.0105	—	3.98948
11.1886	—	3.99635
11.3696	—	4.00322
11.5535	—	4.01012

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

2.82×105 milligrams per kilogram

References (1)

[5] Silicon https://education.jlab.org/itselemental/ele014.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

2.2 milligrams per liter

References (1)

[5] Silicon https://education.jlab.org/itselemental/ele014.html

Sources

Sources of this element.

Silicon is present in the sun and stars and is a principal component of a class of meteorites known as aerolites. It is also a component of tektites, a natural glass of uncertain origin.

Silicon makes up 25.7% of the earth's crust, by weight, and is the second most abundant element, being exceeded only by oxygen. Silicon is not found free in nature, but occurs chiefly as the oxide and as silicates. Sand, quartz, rock crystal, amethyst, agate, flint, jasper, and opal are some of the forms in which the oxide appears. Granite, hornblende, asbestos, feldspar, clay, mica, etc. are but a few of the numerous silicate minerals.

Silicon is prepared commercially by heating silica and carbon in an electric furnace, using carbon electrodes. Several other methods can be used for preparing the element. Amorphous silicon can be prepared as a brown powder, which can be easily melted or vaporized. The Czochralski process is commonly used to produce single crystals of silicon used for solid-state or semiconductor devices. Hyperpure silicon can be prepared by the thermal decomposition of ultra-pure trichlorosilane in a hydrogen atmosphere, and by a vacuum float zone process.

References (1)

[6] Silicon https://periodic.lanl.gov/14.shtml

References

(9)

1 PubChem

Data deposited in or computed by PubChem

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2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

Silicon

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

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4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

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License note: Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.

5 Jefferson Lab, U.S. Department of Energy

Silicon

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html

6 Los Alamos National Laboratory, U.S. Department of Energy

Silicon

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory

Silicon

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements

Silicon

This section provides all form of data related to element Silicon.

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9 PubChem Elements

Silicon

The element property data was retrieved from publications.

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Last updated: May 1, 2026

Data verified: May 12, 2026

Content is reviewed against latest scientific data.