けい素 化学特性,用途語,生産方法
外観
銀灰色〜青灰色, 塊
溶解性
水に不溶。水酸化ナトリウム溶液に溶け、水にほとんど溶けない。
解説
Si．原子番号14の元素．周期表14族元素半金属の一つ．電子配置[Ne]3s23p2．原子量28.0855(3)．質量数28(92.223(19)％)，29(4.685(8)％)，30(3.092(11)％)の3種の安定同位体と22から44までの放射性同位体が知られている．32Si がもっとも長寿命で半減期153 y の β－ 崩壊核種．1824年，J.J. Berzelius(ベルセリウス)が無定形ケイ素の分離に成功，結晶は1854年，H.S-C. Devilleによって得られた．元素名は，1808年にH. Davy(デイビー)がラテン語の“ひうち石”silexからsiliciumを提案，炭素と同族であることから語尾をonに替えて英語元素名がsiliconとなった．フランス語，ドイツ語の元素名はSilicium．蘭学者宇田川榕菴の「舎密開宗」(1837年)には悉里叟母(シリシウム)と記載されている．日本語名ケイ素はけい土に含まれる元素として命名された．
灰白色金属光沢をもつ結晶．ダイヤモンド型構造をもつ.格子定数α ＝ 0.5430 nm，融点1410 ℃，沸点2355 ℃．密度2.3296 g cm－3(25 ℃)．無定形ケイ素は褐色粉末．地殻には，単体ケイ素の形では産しないが，ケイ酸塩の形で大量に存在し，重量百分率で26.77％ を占める．石英(けい砂，水晶)のような酸化物の形でも多量に産する．
用途
シランおよびシリコンの原料、セミコンダクター原料、フェロシリコンなどの合金、高温反応時の還元剤
化学的特性
Silicon is a nonmetallic element which is known as silicon metal. Not occur freely in nature, but is found in silicon dioxide (silica) and in various silicates. It is a steel-gray crystalline solid or a black-brown amorphous material.
物理的性質
Silicon does not occur free in nature, but is found in most rocks, sand, and clay. Siliconis electropositive, so it acts like a metalloid or semiconductor. In some ways silicon resemblesmetals as well as nonmetals. In some special compounds called polymers, silicon will act inconjunction with oxygen. In these special cases it is acting like a nonmetal.
There are two allotropes of silicon. One is a powdery brown amorphous substance bestknown as sand (silicon dioxide). The other allotrope is crystalline with a metallic grayishluster best known as a semiconductor in the electronics industry. Individual crystals of siliconare grown through a method known as the Czochralski process. The crystallized siliconis enhanced by “doping” the crystals (adding some impurities) with other elements such asboron, gallium, germanium, phosphorus, or arsenic, making them particularly useful in themanufacture of solid-state microchips in electronic devices.
The melting point of silicon is 1,420°C, its boiling point is 3,265°C, and its density is2.33 g/cm
3.
同位体
There are 21 isotopes of silicon, three of which are stable. The isotope Si-28makes up 92.23% of the element’s natural abundance in the Earth’s crust, Si-29 constitutes4.683% of all silicon found in nature, and the natural abundance of Si-30 ismerely 3.087% of the stable silicon isotopes found in the Earth’s crust.
名前の由来
Silicon was named after the Latin word silex, which means “flint.”
天然物の起源
Silicon, in the form of silicon dioxide (SiO
2), is the most abundant compound in theEarth’s crust. As an element, silicon is second to oxygen in its concentration on Earth, yet it is only the seventh most abundant in the entire universe. Even so, silicon is used as the standard(Si = 1) to estimate the abundances of all other elements in the universe. For example, hydrogenequals 40,000 times the amount of silicon in the cosmos. Hydrogen is the most abundantof all elements in the universe, and carbon is just three and half times as abundant as siliconin the entire universe. On Earth silicon accounts for 28% of the crust, oxygen makes up 47%of the crust, and much of the rest of the crust is composed of aluminum.
It is believed that silicon is the product of the cosmic nuclear reaction in which alpha particleswere absorbed at a temperature of 10
9 Kelvin into the nuclei of carbon-12, oxygen-16,and neon-20. Pure elemental silicon is much too reactive to be found free in nature, but it doesform many compounds on Earth, mainly oxides as crystals (quartz, cristobalite, and tridymite)and amorphous minerals (agate, opal, and chalcedony). Elemental silicon is produced byreducing silica (SiO
2) in a high-temperature electric furnace, using coke as the reducing agent.It is then refined. Silicon crystals used in electronic devices are “grown” by removing startercrystals from a batch of melted silicon.
特性
The characteristics of silicon in some ways resemble those of the element germanium,which is located just below it in the carbon group.
Flint is the noncrystalline form of silicon and has been known to humans since prehistorictimes. When struck with a sharp blow, flint would flake off sharp-edged chips that were thenused as cutting tools and weapons.
In addition to silica (silicon dioxide SiO
2), the crystal form of silicon is found in severalsemiprecious gemstones, including amethyst, opal, agate, and jasper, as well as quartz of varyingcolors. A characteristic of quartz is its piezoelectric effect. This effect occurs when thequartz crystal is compressed, producing a weak electrical charge. Just the opposite occurs whenelectric vibrations are fed to the crystal. These vibrations are then duplicated in the crystal.Quartz crystals are excellent timekeeping devices because of this particular characteristic.
使用
In making silanes and silicones, the Si-C bond being about as strong as a C-C bond. In the manufacture of transistors, silicon diodes and similar semiconductors. For making alloys such as ferrosilicon, silicon bronze, silicon copper. As a reducing agent like aluminum in high tempereture reactions.
定義
silicon: Symbol Si. A metalloid element belonging to group 14 (formerlyIVB) of the periodic table; a.n.14; r.a.m. 28.086; r.d. 2.33; m.p.1410°C; b.p. 2355°C. Silicon is thesecond most abundant element inthe earth’s crust (25.7% by weight) occurring in various forms of silicon(IV)oxide (e.g. quartz) and in silicateminerals. The element is extractedby reducing the oxide with carbon inan electric furnace and is used extensivelyfor its semiconductor properties.It has a diamond-like crystalstructure; an amorphous form alsoexists. Chemically, silicon is less reactivethan carbon. The element combineswith oxygen at red heat and isalso dissolved by molten alkali. Thereis a large number of organosiliconcompounds (e.g. siloxanes) althoughsilicon does not form the range ofsilicon–hydrogen compounds andderivatives that carbon does (seesilane). The element was identifiedby Antoine Lavoisier in 1787 andfirst isolated in 1823 by J?ns Berzelius.
反応性
Si is a little soluble in water (Solubility: 0.005 g/100 g H2O (298 K)). It reacts strongly with F at room temperature, Cl at 430℃, Br at 500℃, O at 400℃, and N2 at 1000℃ to form compounds of SiF4 , SiCl4 , SiBr4 , SiO2 , SiO, and Si3N4 , respectively.
一般的な説明
A dark brown powder. Insoluble in water and denser than water. Burns readily when exposed to heat or flames, and may be difficult to extinguish. Water may not be effective in extinguishing flames. Used to make computer microchips.
空気と水の反応
Highly flammable. Insoluble in water. A significant dust explosion hazard.
反応プロフィール
Silicon is a reducing agent. Ignites in fluorine gas at ordinary temperatures [Mellor 2:11-13 1946-47]. Burns spontaneously in gaseous chlorine. A mixture of silicon, aluminum, and lead oxide explodes when heated [Mellor 7:657 1946-47]. When heated with an alkali carbonate, a vigorous reaction attended by incandescence occurs [Mellor 6:164 1946-47]. Reacts violently with silver fluoride [Mellor 3:389 1946-47]. Reacts with sodium-potassium alloy to form sodium silicide, which is spontaneously flammable in air [Mellor 2 Supp. 2:564 1961].
危険性
The dust of silicon oxide (silicate) can burn or explode and is very harmful if inhaled.Continued exposure to silica dust causes silicosis, a form of pneumonia.
The hydrides of silicon (silicon plus hydrogen) are extremely volatile and spontaneouslyburst into flames in air at room temperatures. They must be kept in special vacuum chambers.
Over the past several decades, there has been some concern over the potential hazards andsafety of the cosmetic use of silicone body implants—breast implants, in particular. Severalmanufactures have been sued over the failure of the implants, and the federal government (FDA) withdrew its approval for their use. Congressional hearings with manufacturers in2005 produced new information that has reversed the FDA’s ban on their use—but only withcertain manufacturers of implants. The debate continues.
健康ハザード
Oxides from metallic fires are a severe health hazard. Inhalation or contact with substance or decomposition products may cause severe injury or death. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause pollution.
火災危険
May react violently or explosively on contact with water. Some are transported in flammable liquids. May be ignited by friction, heat, sparks or flames. Some of these materials will burn with intense heat. Dusts or fumes may form explosive mixtures in air. Containers may explode when heated. May re-ignite after fire is extinguished.
工業用途
Silicon is, after oxygen, the second most abundant element in the earth s crust. It occurs in a range of minerals and sand (SiO2, quartz). Silicon can be extracted from silicates or sand by reducing SiO2 with coke at high temperatures at around 3000°C.Silicon is used in a wide variety of applications. In nature, silicon does not exist as the pure metal and most commonly occurs in silica (including sand) and silicates. Silicon dioxide, also known as silica, is a hard substance with a high melting temperature and clearly very different from carbon dioxide. Molten silica can be used to make glass, an extremely useful material, which is resistant to attack by most chemicals except fluorine, hydrofluoric acid and strong alkalis. Silicon atoms can also be found in the class of compounds called silicones. Pure silicon metal is used in semiconductors, the basis of all electronic devices, and is most well known for its application in solar panels and computer chips.
安全性プロファイル
A nuisance dust. Moderately toxic by ingestion. An eye irritant. Does not occur freely in nature, but is found as sdicon dioxide (sdtca) and as various shcates. Elemental Si is flammable when exposed to flame or by chemical reaction with oxidlzers. Violent reactions with alkali carbonates, oxidants, (A1 + PbO), Ca, Cs2C2, Cl2, CoF2, F2, IFs, MnF3, Rb2C2, FNO, AgF, NaK alloy. When heated it will react with water or steam to produce H2; can react with oxidizing materials. See also various silica entries, SILICATES, and POWDERED METALS.
職業ばく露
Silicon may be used in the manufacture of silanes, silicon tetrachloride, ferrosilicon, silicones. It is used in purified elemental form in transistors and photovoltaic cells.
輸送方法
UN1346 Silicon powder, amorphous requires, Hazard Class: 4.1; Labels: 4.1-Flammable solid.
不和合性
Dust or powder may form explosive mixture with air. A strong reducing agent. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, calcium, carbonates, chlorine, fluorine, oxidizers, cesium carbide; alkaline carbonates.
けい素 上流と下流の製品情報
原材料
準備製品