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Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive.
- crystalline, reflective with bluish-tinged faces
- see Allotropes of silicon
- Overview
- Occurrence and distribution
- Properties of the element
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silicon (Si), a nonmetallic chemical element in the carbon family (Group 14 [IVa] of the periodic table). Silicon makes up 27.7 percent of Earth’s crust; it is the second most abundant element in the crust, being surpassed only by oxygen.
The name silicon derives from the Latin silex or silicis, meaning “flint” or “hard stone.” Amorphous elemental silicon was first isolated and described as an element in 1824 by Jöns Jacob Berzelius, a Swedish chemist. Impure silicon had already been obtained in 1811. Crystalline elemental silicon was not prepared until 1854, when it was obtained as a product of electrolysis. In the form of rock crystal, however, silicon was familiar to the predynastic Egyptians, who used it for beads and small vases; to the early Chinese; and probably to many others of the ancients. The manufacture of glass containing silica was carried out both by the Egyptians—at least as early as 1500 bce—and by the Phoenicians. Certainly, many of the naturally occurring compounds called silicates were used in various kinds of mortar for construction of dwellings by the earliest people.
On a weight basis, the abundance of silicon in the crust of Earth is exceeded only by oxygen. Estimates of the cosmic abundance of other elements often are cited in terms of the number of their atoms per 106 atoms of silicon. Only hydrogen, helium, oxygen, neon, nitrogen, and carbon exceed silicon in cosmic abundance. Silicon is believed to be a cosmic product of alpha-particle absorption, at a temperature of about 109 K, by the nuclei of carbon-12, oxygen-16, and neon-20. The energy binding the particles that form the nucleus of silicon is about 8.4 million electron volts (MeV) per nucleon (proton or neutron). Compared with the maximum of about 8.7 million electron volts for the nucleus of iron, almost twice as massive as that of silicon, this figure indicates the relative stability of the silicon nucleus.
Pure silicon is too reactive to be found in nature, but it is found in practically all rocks as well as in sand, clays, and soils, combined either with oxygen as silica (SiO2, silicon dioxide) or with oxygen and other elements (e.g., aluminum, magnesium, calcium, sodium, potassium, or iron) as silicates. The oxidized form, as silicon dioxide and particularly as silicates, is also common in Earth’s crust and is an important component of Earth’s mantle. Its compounds also occur in all natural waters, in the atmosphere (as siliceous dust), in many plants, and in the skeletons, tissues, and body fluids of some animals.
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Elemental silicon is produced commercially by the reduction of silica (SiO2) with coke in an electric furnace, and the impure product is then refined. On a small scale, silicon can be obtained from the oxide by reduction with aluminum. Almost pure silicon is obtained by the reduction of silicon tetrachloride or trichlorosilane. For use in electronic devices, single crystals are grown by slowly withdrawing seed crystals from molten silicon.
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Pure silicon is a hard, dark gray solid with a metallic lustre and with a octahedral crystalline structure the same as that of the diamond form of carbon, to which silicon shows many chemical and physical similarities. The reduced bond energy in crystalline silicon renders the element lower melting, softer, and chemically more reactive than diamond. A brown, powdery, amorphous form of silicon has been described that also has a microcrystalline structure.
Because silicon forms chains similar to those formed by carbon, silicon has been studied as a possible base element for silicon organisms. The limited number of silicon atoms that can catenate, however, greatly reduces the number and variety of silicon compounds compared with those of carbon. The oxidation–reduction reactions do not appear to be reversible at ordinary temperatures. Only the 0 and +4 oxidation states of silicon are stable in aqueous systems.
Silicon, like carbon, is relatively inactive at ordinary temperatures; but when heated it reacts vigorously with the halogens (fluorine, chlorine, bromine, and iodine) to form halides and with certain metals to form silicides. As is true with carbon, the bonds in elemental silicon are strong enough to require large energies to activate, or promote, reaction in an acidic medium, so it is unaffected by acids except hydrofluoric. At red heat, silicon is attacked by water vapour or by oxygen, forming a surface layer of silicon dioxide. When silicon and carbon are combined at electric furnace temperatures (2,000–2,600 °C [3,600–4,700 °F]), they form silicon carbide (carborundum, SiC), which is an important abrasive. With hydrogen, silicon forms a series of hydrides, the silanes. When combined with hydrocarbon groups, silicon forms a series of organic silicon compounds.
Silicon is a nonmetallic chemical element in the carbon family, abundant in Earth's crust and cosmos. It forms compounds with oxygen (silica and silicates) and other elements, and has various applications in electronics, glass, and biology.
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Element Silicon (Si), Group 14, Atomic Number 14, p-block, Mass 28.085. Sources, facts, uses, scarcity (SRI), podcasts, alchemical symbols, videos and images.
Apr 27, 2018 · Silicon is the seventh-most abundant element in the universe and the second-most abundant element on the planet, after oxygen, according to the Royal Society of Chemistry. About 25 percent of the...
Definition, mass & chemical names. Silicon. Silicon is the second most abundant element in earth’s crust. It was discovered in 1823 by Jöns Jacob Berzelius. Silicon has tremendous uses including manufacturing of ceramic, glass, synthetic polymers and is an essential part of integrated circuits.
Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it.
Learn about silicon, the second most abundant element in Earth's crust, and its properties, uses, and compounds. Find out how silicon is related to oxygen, metals, and semiconductors, and who discovered it.
