Crystalline silicon is dark blue and fragile, which is a typical semiconductor. The chemical properties are very stable. It is difficult to react with substances other than hydrogen fluoride at room temperature.
Uses of silicon:
① High purity monocrystalline silicon is an important semiconductor material. Doping trace amounts of IIIA elements into monocrystalline silicon to form a P-type silicon semiconductor; By doping a small amount of VA group elements to form N-type and P-type semiconductors, solar cells can convert radiant energy into electric energy. It is a promising material for developing energy.
(2) cermets and important materials for aerospace. Ceramic and metal are mixed and sintered to make cermet composite material, which has high temperature resistance, high toughness and machinability. It not only inherits the advantages of metals and ceramics, but also makes up for their inherent defects. It can be used to make military weapons. The first space shuttle "Columbia" can withstand the high temperature caused by friction when it passes through the dense atmosphere at high speed, thanks to its shell made of 3 1000 silicon tiles.
③ Optical fiber communication, the latest modern communication means. Drawing high transparency glass fiber with pure silica. In the path of glass fiber, the laser travels forward through countless total reflections, instead of heavy cables. Optical fiber has high communication capability. A glass fiber as thin as hair can transmit 256 calls at the same time. It is not disturbed by electricity and magnetism, and it is not afraid of eavesdropping, so it is highly confidential. Optical fiber communication will completely change human life in 2 1 century.
④ silicone organic compounds with excellent performance. For example, silicone plastic is an excellent waterproof coating material. Spraying silica gel on subway walls can solve the problem of water seepage once and for all. Coating a thin layer of silica gel on the surface of ancient cultural relics and sculptures can prevent the growth of moss, prevent wind, rain and wind. The Monument to the People's Heroes in Tiananmen Square is made of silica gel, so it is always white and fresh.
find
1822, Swedish chemist Bertie reduced silicon tetrafluoride with metal potassium to obtain simple silicon.
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The origin of the name
Derived from the English word silica, which means "silica".
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Be distributed
Silicon mainly exists in the form of compounds. As the most abundant element after oxygen, it occupies about a quarter of the surface rocks and widely exists in silicates and silica.
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prepare
In industry, it is usually made by reducing silicon dioxide with carbon in an electric furnace.
Chemical reaction equation:
Silicon dioxide+2C → silicon+2CO
The purity of silicon prepared in this way is 97~98%, which is called metallic silicon. Then melting and recrystallizing, and removing impurities with acid to obtain metallic silicon with the purity of 99.7-99.8%. If semiconductor silicon is to be made, it must be converted into liquid or gas form that is easy to purify, and then polysilicon can be obtained by distillation decomposition. If high-purity silicon is to be obtained, further purification treatment is needed.
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isotope
Silicon has 12 isotopes, including silicon 25 to silicon 36, of which only silicon 28, silicon 29 and silicon 30 are stable, and other isotopes are radioactive.
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use
Silicon is a semiconductor material, which can be used to make semiconductor devices and integrated circuits. It can also be used in automobile and mechanical parts in the form of alloy (such as ferrosilicon alloy). It is also used in cermets of ceramic materials. It can also be used to make glass, concrete, bricks, refractories, siloxanes and silanes.
Characteristics of silicon, aluminum, silicon and phosphorus
carbon
silicon (Si)
germanium (Ge)
periodic table of elements
Overall characteristics
Name, symbol, serial number Si, Si, 14
Series nonmetal
Series, period, element partition 14 series (IVA), 3, p
The density and hardness are 2330 kg/m3 and 6.5 respectively.
The color and appearance are dark gray with blue tones.
The crust content is 25.7%
Atomic properties
Atomic weight 28.0855 atomic weight unit
Atomic radius (calculated value)110 (11) pm.
* * * The price radius is 1 1 1 pm.
Van der Waals radius 2 10 pm
Valence electron configuration [neon ]3s23p2
The arrangement of electrons at each energy level 2, 8 and 4.
Oxidation number (oxide) 4 (amphoteric)
Face-centered cubic crystal structure
physical quality
Material state solid state
Melting point1687k (1414 c)
Boiling point: 3 173 k (2900 c)
The molar volume is 12.06× 10-6m3/mol.
The heat of vaporization is 384.22 kJ/mol.
Heat of fusion 50.55 kJ/mol
The vapor pressure is 4.77 Pa (1683K).
The speed of sound without data
Other attributes
Electronegativity 1.90 (Pauling scale)
Specific heat 700 Joule/(kg kg)
The electrical conductivity is 2.52× 10-4/(m ohms).
Thermal conductivity148 w/(m k)
The first ionization energy is 786.5 kJ/mol.
The second ionization energy is 1577. 1 kJ/mol.
The third ionization energy is 323 1.6 kJ/mol.
The fourth ionization energy is 4355.5 kJ/mol.
The fifth ionization energy is 1609 1 kJ/mol.
The sixth ionization energy is 19805 kJ/mol.
The seventh ionization energy is 23780 kJ/mol.
The eighth ionization energy is 29287 kJ/mol.
The ninth ionization energy is 33878 kJ/mol.
The tenth ionization energy is 38726 kJ/mol.
The most stable isotope
Decay energy of isotope abundance half-life decay mode
MeV decay products
28Si 92.23% stable
29Si 4.67% stable
30Si 3. 1% stable
32Si Artificial 276 β Decay 0.224 32P
Nuclear magnetic resonance characteristics
29Si
Nuclear spin 1/2
Element Name: Silicon
Atomic weight of element: 28.09
Element type: nonmetal
Discoverer: Bethelius. Found in 1823.
Discovery process:
In 1823 of Bethelius, Sweden, silicon fluoride or potassium fluorosilicate is heated together with potassium to obtain powdered silicon.
Element description:
It consists of amorphous and crystalline allotropes. It has obvious metallic luster, gray color, density of 2.32-2.34g/cm3, melting point 14 10℃, boiling point of 2355℃, diamond crystal structure and ionization energy of 8. 15 1 eV. When heated, it can react with nonmetals such as halogen, nitrogen and carbon, and also with some metals such as magnesium, calcium, iron and platinum. Generate silicide. Insoluble in general inorganic acid, soluble in alkali solution, releasing hydrogen to form corresponding alkali metal silicate solution, which can react with water vapor at red-hot temperature. Silicon is widely distributed in nature, and its atomic percentage in the crust is 16.7%. It is the basic element of rock minerals and appears in the form of quartz sand and silicate.
Element source:
Amorphous silicon can be obtained by reducing silicon dioxide with magnesium. Crystalline silicon can be obtained by reducing silicon dioxide with carbon in an electric furnace. High-purity silicon used in electronic industry is made by reducing trichlorosilane or silicon tetrachloride with hydrogen.
Element usage:
Used for manufacturing high silicon cast iron, silicon steel and other alloys, organosilicon compounds and silicon tetrachloride. It is an important semiconductor material. Silicon single crystal doped with trace impurities can be used to manufacture high-power transistors, rectifiers and solar cells.
Element auxiliary data:
Silicon is the most abundant element in the earth's crust except oxygen. If carbon is the basis of all organic life, then silicon also occupies the same position for the earth's crust, because the main part of the earth's crust is composed of layers of rocks containing silicon. Almost all of these rocks are composed of silica and various silicates.
Feldspar, mica, clay, olivine and amphibole are all silicates; Crystal, agate, tourmaline, opal, timely, sand and flint are all silica. However, unlike oxygen and carbon, silicon has no elemental state in nature. This is destined to be discovered later than carbon and oxygen.
Lavoisier once regarded silicon dioxide as an inseparable material element.
In 1823, Bezirius prepared amorphous silicon from potassium fluosilicate (K2SiF6) and excess potassium. Although many scientists have made amorphous silicon before, silicon was not identified as an element until Bezirius burned silicon in oxygen to produce silica-silica soil. Silicon is named silicon, and the element symbol is Si.
graphical user interface
silicon (Si)
Silicon;
silicon (Si)
ancient
A tetravalent nonmetallic element, which exists in the earth's crust as a compound, is the most abundant element after oxygen. It is usually made by reducing silicon dioxide with carbon in an electric furnace. It is mainly used in the form of alloy (such as ferrosilicon alloy), and also used in cermets together with ceramic materials, or as a component of semiconductor materials (such as transistors) and photovoltaic cells-element symbol Si.
Non-metallic element is a kind of semiconductor material, which can be used to manufacture semiconductor devices and integrated circuits. Formerly known as "silicon".
Element symbol Si, formerly known as silicon, has an atomic number of 14 and a relative atomic mass of 28.09. There are two kinds of allotropes: amorphous and crystalline.
Crystalline silicon is steel gray and amorphous silicon is black, with a density of 2.4g/cm3, a melting point of 1420℃ and a boiling point of 2355℃. Crystalline silicon is an atomic crystal, hard and shiny, with semiconductor characteristics. Silicon has active chemical properties and can combine with oxygen and other elements at high temperature. Insoluble in water, nitric acid and hydrochloric acid, soluble in hydrofluoric acid and alkali solution, used to make ferrosilicon, silicon steel and other alloys. Monocrystalline silicon is an important semiconductor material, which is used to manufacture high-power transistors, rectifiers, solar cells and so on. Silicon is widely distributed in nature, accounting for about 27.6% in the earth's crust, mainly in the form of silicon dioxide and silicate.
Silicon, atomic number 14, atomic weight 28.0855, element name comes from Latin, meaning "flint". 1823, the Swedish chemist Betzerius first separated and described silicon. Silicon accounts for about 27.72% of the total weight of the earth's crust, second only to oxygen. Silicon exists in the form of oxygenated compounds in nature. Seasons, crystals and sand are common.
Silicon has two forms: crystalline and amorphous. Crystalline silicon has a rhombic lattice, which is hard and brittle, with melting point 14 10℃, boiling point of 2355℃ and density of 2.32 ~ 2.34 g/cm? , the hardness is 7. Amorphous silicon is a kind of gray-black powder, which is actually microcrystal. The conductivity of crystalline silicon is not as good as that of metal, and it increases with the increase of temperature, so it has obvious semiconductor characteristics.
Silicon is inactive at room temperature and has no obvious effect on air, water and acid. Under heating, it can react with halogen to produce silicon tetrahalide; At 650°C, silicon begins to completely react with oxygen; Silicon can also react with nonmetallic elements such as carbon, nitrogen and sulfur at high temperature; Silicon can indirectly generate a series of silicon hydride; Silicon can also combine with calcium, magnesium and iron. To form metal silicide.
Ultra-pure monocrystalline silicon can be used as semiconductor material. Alloys of crude monocrystalline silicon and its intermetallic compounds are commonly used to strengthen metals such as aluminum, magnesium and copper.