Silicon (Si)
metalloidSolid
Standard Atomic Weight
28.085 u [28.084, 28.086]Electron configuration
[Ne] 3s2 3p2Melting point
1413.85 °CBoiling point
3264.85 °CDensity
2329.6 kg/m³Oxidation states
−4, −3, −2, −1, 0, +1, +2, +3, +4Electronegativity (Pauling)
1.9Ionization energy (1st)
8.15168 eVDiscovery year
1824Atomic radius
110 pmDetails
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.
Pure crystalline silicon is a dark gray solid with a metallic luster and a diamond-cubic structure. It is brittle rather than malleable. Amorphous silicon is usually a brown to dark gray powder or thin film, with properties that depend strongly on preparation.
High-purity silicon is used for integrated circuits, power electronics, sensors, and photovoltaic cells. Lower-purity metallurgical silicon is used to make aluminum-silicon casting alloys, silicones, silanes, and silica-derived materials. Ferrosilicon is an important deoxidizer and alloying additive in steelmaking. Silicon carbide abrasives and refractories are often produced from silica and carbon, but their use depends on the compound rather than the free element.
Two allotropes of silicon exist at room temperature: amorphous and crystalline. Amorphous appears as a brown powder while crystalline silicon has a metallic luster and a grayish color. Single crystals of crystalline silicon can be grown with a process known as the Czochralski process. These crystals, when doped with elements such as boron, gallium, germanium, phosphorus or arsenic, are used in the manufacture of solid-state electronic devices, such as transistors, solar cells, rectifiers and microchips.
Silicon dioxide (SiO2), silicon's most common compound, is the most abundant compound in the earth's crust. It commonly takes the form of ordinary sand, but also exists as quartz, rock crystal, amethyst, agate, flint, jasper and opal. Silicon dioxide is extensively used in the manufacture of glass and bricks. Silica gel, a colloidal form of silicon dioxide, easily absorbs moisture and is used as a desiccant.
Silicon forms other useful compounds. Silicon carbide (SiC) is nearly as hard as diamond and is used as an abrasive. Sodium silicate (Na2SiO3), also known as water glass, is used in the production of soaps, adhesives and as an egg preservative. Silicon tetrachloride (SiCl4) is used to create smoke screens. Silicon is also an important ingredient in silicone, a class of material that is used for such things as lubricants, polishing agents, electrical insulators and medical implants.
Silicon is one of man's most useful elements. In the form of sand and clay it is used to make concrete and brick; it is a useful refractory material for high-temperature work, and in the form of silicates it is used in making enamels, pottery, etc. Silica, as sand, is a principal ingredient of glass, one of the most inexpensive of materials with excellent mechanical, optical, thermal, and electrical properties. Glass can be made in a very great variety of shapes, and is used as containers, window glass, insulators, and thousands of other uses. Silicon tetrachloride can be used as iridize glass.
Hyperpure silicon can be doped with boron, gallium, phosphorus, or arsenic to produce silicon for use in transistors, solar cells, rectifiers, and other solid-state devices which are used extensively in the electronics and space-age industries.
Hydrogenated amorphous silicon has shown promise in producing economical cells for converting solar energy into electricity.
Silicon is important to plant and animal life. Diatoms in both fresh and salt water extract Silica from the water to build their cell walls. Silica is present in the ashes of plants and in the human skeleton. Silicon is an important ingredient in steel; silicon carbide is one of the most important abrasives and has been used in lasers to produce coherent light of 4560 A.
Silcones are important products of silicon. They may be prepared by hydrolyzing a silicon organic chloride, such as dimethyl silicon chloride. Hydrolysis and condensation of various substituted chlorosilanes can be used to produce a very great number of polymeric products, or silicones, ranging from liquids to hard, glasslike solids with many useful properties.
Isotopes in Earth/Planetary Science
Because molecules, atoms, and ions of the stable isotopes of silicon possess slightly different physical and chemical properties, they commonly will be fractionated during physical, chemical, and biological processes, giving rise to variations in isotopic abundances and in atomic weights. There are substantial variations in the isotopic abundances of silicon in natural terrestrial materials (Fig. IUPAC.14.1). These variations are useful in investigating the origin of substances and studying environmental, hydrological, and geological processes [13] M. W. Wieser, T. B. Coplen. Pure Appl Chem.83, 359 (2011)., [17] T. B. Coplen, J. A. Hopple, J. K. Böhlke, H. S. Peiser, S. E. Rieder, H. R. Krouse, K. J. R. Rosman, T. Ding, R. D. Vocke, K. Revesz, A. Lamberty, P. D. P. Taylor, P. D. Bièvre. United States Geological Survey Water-Resources Investigations Report, 01-4222, (2002).. Diatoms, a major group of algae, need silicon to build up their opaline shells and prefer 28Si while taking up Si(OH)4, which is the biologically available form of silicon in the marine environment. This progressively enriches surface waters with 29Si and 30Si [123] S. Kristiansen, T. Farbrot, L. J. Naustvoll. Limnol. Oceanogr.45, 472 (2000).. 32Si-labeled silicic acid of high specific radioactivity is used to measure uptake rates of Si and estimate marine sedimentation of biogenic (created by living organisms) silica (by diatoms and sea shells). By performing uptake kinetic experiments, the 32Si activity can be measured as 32P using counting of Cherenkov radiation (radiation produced by charged particles passing through a medium at a speed greater than that of light through the same medium — after Soviet physicist Pavel A. Cherenkov) with a liquid scintillation analyzer (measuring ionizing radiation using the interaction of radiation on a material and counting the resulting photon emissions).
Isotopes in Geochronology
Cosmogenic 32Si has a half-life of about 150 years and is produced by cosmic-ray spallation of argon in the stratosphere and troposphere [124] C. Schnabel, J. Beer, H. B. Clausen. Geophys. Res. Abstr.11, (2009).. 32Si in dust is precipitated in snow, making it possible to date dust in snow and glacial ice (Fig. IUPAC.14.2). Glaciers are archives for global climate history because they contain a variety of proxies (imprints of past environmental conditions used to interpret paleoclimate) for climate forcing and climate response. Cosmogenic 32Si that is stored in glaciers and ice-core samples can be analyzed using accelerator mass spectrometry to date when sections of glaciers formed [125] SAHRA – Sustainability of Semi-Arid Hydrology and Riparian Areas. Silicon, SAHRA – Sustainability of Semi-Arid Hydrology and Riparian Areas (2014), Feb. 24; http://web.sahra.arizona.edu/programs/isotopes/silicon.html., [126] GNS Science. Climate Change Studies & Ice Core Research, GNS Science (2014), Feb. 24; http://www.gns.cri.nz/Home/Services/Laboratories-Facilities/Tritium-and-Water-Dating-Laboratory/Research-Programmes/Climate-change-studies-ice-core-research..
Isotopes in Industry
At Keio University in Japan, the Itoh Research Group has developed a method that utilizes 29Si to store and process information. The Itoh Research Group focused on manipulating the nanostructure of materials at an atomic level, especially with semiconductors such as silicon. Their manipulations and observations demonstrate that differences in the nuclear spin and mass of an isotope affects the ease of further manipulation of the isotope [128] Kohei ITOH research group at Keio University, Japan. Itoh Group at Keio University, Japan, Kohei ITOH research group at Keio University, Japan (2014), Feb. 24; http://www.appi.keio.ac.jp/Itoh_group/research/., [129] T. Itahashi, H. Hayashi, M. R. Rahman, K. M. Itoh, L. S. Vlasenko, M. P. Vlasenko, D. S. Poloskin. Phys. Rev. B87, 075201-1 (2013)..
Silicon crystals enriched to higher than 99.99 percent purity of 28Si are being used in the Avogadro Project. This project is intended to remeasure the Avogadro constant (NA), which is the proportionality factor between the amount of substance and number of elementary entities [130] R. Marquardt, J. Meija, Z. Mester, M. Towns, R. Weir, R. Davis, J. Stohner. Pure Appl. Chem.90, 175 (2018)..
Silicon chemistry is dominated by the +4 oxidation state, although lower formal states occur in some silicides and specialized molecular compounds. Silicon dioxide, SiO₂, occurs as quartz and many other forms and is the basis of glass, ceramics, and semiconductor gate oxides. Silicates contain SiO₄ tetrahedra in isolated, chain, sheet, or framework arrangements. Silicon tetrachloride, SiCl₄, and trichlorosilane, HSiCl₃, are important intermediates for purified silicon and organosilicon chemistry. Silicones contain Si–O backbones with organic substituents.
See more information at the Silicon compound page.
Bulk crystalline silicon has low chemical toxicity, but fine silicon dust can irritate the eyes and respiratory tract and may pose dust-explosion risks in air. Inhalation hazards are more serious for respirable crystalline silica, SiO₂, which can cause silicosis; that risk belongs to the oxide, not elemental silicon. Silanes such as silane, SiH₄, can be pyrophoric or highly flammable. Semiconductor processing also involves corrosive and toxic reagents not inherent to silicon itself.
Miners, stonecutters, and others engaged in work where siliceous dust is breathed into large quantities often develop a serious lung disease known as silicosis.
Silicon is a major component of soils, rocks, clays, and natural waters, mostly as silicates and dissolved silicic acid, H₄SiO₄. Weathering releases soluble silicon, which rivers carry to lakes and oceans. Diatoms, radiolarians, and some plants use silica biomineralization, linking silicon to biological and sedimentary cycles. Elemental silicon is not persistent as a native environmental material under surface conditions.
Silicon is produced industrially by reducing quartz or other high-silica feedstocks with carbon in electric arc furnaces, yielding metallurgical-grade material. Semiconductor and solar uses require further purification and crystal growth or deposition, which are energy- and capital-intensive steps. Demand is split between large-volume alloy and chemical markets and smaller but very high-purity electronic markets. Recycling occurs in aluminum alloys and semiconductor manufacturing scrap, but end-of-life recovery from complex electronics is limited by dilution and contamination.
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.
Silicon is among the more abundant heavy elements in the cosmos. It is formed in massive stars during advanced burning stages and is further redistributed by supernovae. In rocky planets and meteorites it is chiefly bound with oxygen and metals as silicate minerals. Spectral features of silicate dust are common in interstellar and circumstellar environments.
- The natural oxide on silicon is only a few nanometers thick but is chemically important.
- Ultra-pure silicon crystals can be grown with impurity levels far below one part per billion.
- Dopants such as boron or phosphorus control whether silicon behaves as p-type or n-type semiconductor material.
- Many common gemstones, including quartz varieties, are forms or mixtures dominated by SiO₂.
- Silicon expands on freezing, like water and a few other substances.
Images
Properties
Physical
- Atomic radius (empirical)
- 110 pm Compare Atomic radius (empirical) of all elements →
- Covalent radius
- 111 pm Compare Covalent radius of all elements →
- Van der Waals radius
- 210 pm Compare Van der Waals radius of all elements →
- Metallic radius
- 117 pm Compare Metallic radius of all elements →
- Density
- 2329.6 kg/m³ Compare Density of all elements →
- Molar volume
- 0.0121 L/mol
- Phase at STP
- Solid Compare Phase at STP of all elements →
- Melting point
- 1413.85 °C Compare Melting point of all elements →
- Boiling point
- 3264.85 °C Compare Boiling point of all elements →
- Thermal conductivity
- 149 W/(m·K) Compare Thermal conductivity of all elements →
- Specific heat capacity
- 0.712 J/(g·K) Compare Specific heat capacity of all elements →
- Molar heat capacity
- 19.99 J/(mol·K) Compare Molar heat capacity of all elements →
- Crystal structure
- Diamond cubic Compare Crystal structure of all elements →
Chemical
- Electronegativity (Pauling)
- 1.9 Compare Electronegativity (Pauling) of all elements →
- Electronegativity (Allen)
- 1.916
- Electron affinity
- 1.385 eV
- Ionization energy (1st)
- 8.15168 eV Compare Ionization energy (1st) of all elements →
- Ionization energy (2nd)
- 16.345906 eV Compare Ionization energy (2nd) of all elements →
- Ionization energy (3rd)
- 33.493115 eV Compare Ionization energy (3rd) of all elements →
- Ionization energy (4th)
- 45.141945 eV Compare Ionization energy (4th) of all elements →
- Ionization energy (5th)
- 166.767574 eV Compare Ionization energy (5th) of all elements →
- Oxidation states
- −4, −3, −2, −1, 0, +1, +2, +3, +4 Compare Oxidation states of all elements →
- Valence electrons
- 4 Compare Valence electrons of all elements →
- Electron configuration
- [Ne] 3s2 3p2
Thermodynamic
- Heat of fusion
- 0.52039177 eV Compare Heat of fusion of all elements →
- Heat of vaporization
- 3.720786 eV Compare Heat of vaporization of all elements →
- Heat of sublimation
- 4.670778 eV
- Heat of atomization
- 4.670778 eV
- Atomization enthalpy
- 4.663937 eV
Nuclear
- Protons
- 14 Compare Protons of all elements →
- Neutrons
- 14 Compare Neutrons of all elements →
- Known isotopes
- 24 Compare Known isotopes of all elements →
- Stable isotopes
- 3 Compare Stable isotopes of all elements →
- Most stable isotope
- Si-28
- Discovery year
- 1824
Abundance
- Abundance (Earth's crust)
- 2.82e+5 mg/kg Compare Abundance (Earth's crust) of all elements →
- Abundance (ocean)
- 2.2 mg/L Compare Abundance (ocean) of all elements →
Crystal Structure
- Lattice constant a
- 543 pm
Electronic Structure
- Electrons per shell
- 2, 8, 4 Compare Electrons per shell of all elements →
Identifiers
- CAS number
- 7440-21-3 Compare CAS number of all elements →
- Term symbol
- 3P0
- InChI
- InChI=1S/Si
- InChI Key
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N
Electron Configuration Measured
Si: 3s² 3p²[Ne] 3s² 3p²1s² 2s² 2p⁶ 3s² 3p²Atomic model
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
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 |
Phase / State
Reason: 1388.8 °C below melting point (1413.85 °C)
Schematic, not to scale
Phase transition points
Transition energies
Energy required to melt 1 mol at melting point
Energy required to vaporize 1 mol at boiling point
Energy required to sublime 1 mol at sublimation point
Density
At standard conditions
At standard conditions
Atomic Spectra
Showing 10 of 14. 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 |
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 |
Ionic Radii
| Charge | Coordination | Spin | Radius |
|---|---|---|---|
| +4 | 4 | N/A | 26 pm |
| +4 | 6 | N/A | 40 pm |
Compounds
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 |
Spectral Lines
Showing 50 of 474. 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)
- 116 pm
- Covalent radius (Pyykkö, double)
- 107 pm
- Covalent radius (Pyykkö, triple)
- 102 pm
- Covalent radius (Bragg)
- 117 pm
Van der Waals Radii
- Bondi
- 210 pm
- Batsanov
- 210 pm
- Alvarez
- 219 pm
- UFF
- 429.5 pm
- MM3
- 229 pm
- Dreiding
- 427 pm
Atomic & Metallic Radii
- Atomic radius (Rahm)
- 232 pm
- Metallic radius (C12)
- 138 pm
Numbering Scales
- Mendeleev
- 88
- Pettifor
- 85
- Glawe
- 85
Electronegativity Scales
- Ghosh
- 0
- Miedema
- 5
- Gunnarsson–Lundqvist
- 5
- Robles–Bartolotti
- 4
Polarizability & Dispersion
- Dipole polarizability
- 37.3 a.u.
- Dipole polarizability (unc.)
- 0.7 a.u.
- C₆
- 305 Ha·Bohr6
- C₆ (Gould–Bučko)
- 308 Ha·Bohr6
Chemical Affinity
- Proton affinity
- 837 kJ/mol
- Gas basicity
- 814.1 kJ/mol
Miedema Parameters
- Miedema molar volume
- 8.6 cm3/mol
- Miedema electron density
- 3
Phase Transitions & Allotropes
| Melting point | 1687.15 K |
| Boiling point | 3538.15 K |
Oxidation State Categories
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 | rcrystal (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)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
2.2 milligrams per liter
References (1)
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)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
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.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
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/
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.
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
This section provides all form of data related to element Silicon.
The element property data was retrieved from publications.