oldleft.blogg.se - Compounds of silicon

#Compounds of silicon skin
#Compounds of silicon free

Silica is composed of one silicon atom with four single bonds to four oxygen molecules (Figure 2). Silica is not a silicon atom with two double bonds to two oxygen atoms. Silica is the one stable oxide of silicon, and has the empirical formula SiO 2. Silicon is most commonly found in silicate compounds. This is a form of chemical vapor deposition where gaseous trichlorosilane is blown across a pure silicon rod to grow polycrystalline silicon (polysilicon) with a purity of 99.9999%.\) The Siemens process is another method used to produce high purity silicon. Molten salt electrolysis of silica (silicon dioxide) or other silicon compounds can be used to obtain the element at >99.9% purity for use in semiconductors. Silicon is available at extremely high purity.The Occupational Safety and Health Administration (OSHA) sets the legal limit for workplace exposure to silicon to 15 mg/m 3 total exposure and 5 mg/m 3 respiratory exposure for an 8-hour workday.

#Compounds of silicon skin

Exposure to silicon may occur by inhalation, ingestion, skin contact, and eye contact.

Miners, stone cutters, and people who live in sandy regions may inhale large quantities of silicon compounds and develop a lung disease called silicosis.

At least twenty radioisotopes are also known, with the most stable being silicon-32, which has a half-life of 170 years. Silicon-28 is the most abundant, accounting for 92.23% of the natural element.

Natural silicon consists of three stable isotopes: silicon-28, silicon-29, and silicon-30.

Like water (and unlike most chemicals), silicon has a higher density as a liquid than as a solid.

Because silicate minerals are common, silicon oxides form rocks and are used to make glass and ceramics. The compound silicon carbide is an important abrasive. The element is purified to make semiconductors and other electronics.

Most silicon is used to produce the alloy ferrosilicon.

Dietary supplementation with silicon may increase bone density and reduce the risk of osteoporosis. Humans need silicon for healthy skin, hair, nails, and bones, and to synthesize the proteins collagen and elastin. Some aquatic organisms, such as diatoms, use the element to construct their skeletons. Silicon is needed for plant and animal life.It's the principal element in a type of meteorite called aerolites. It's the 8th most abundant element in the universe, found at levels of about 650 parts per million.

#Compounds of silicon free

It's commonly encountered in silicate minerals, such as quartz and sand, but only rarely occurs as a free element. Silicon is the second most abundant element on Earth by mass, making up over 27% of the crust.Like carbon, it usually has a valence of 4 (tetravalent), but unlike carbon, silicon can also form five or six bonds.

Silicon has a high thermal conductivity and conducts heat well. Unlike metals, it's brittle, and not malleable or ductile. Silicon conducts electricity better than nonmetals, yet not as well as metals. Amorphous silicon is usually seen as a gray powder, while crystalline silicon is a gray solid with a shiny, metallic appearance. Like other metalloids, silicon has different forms or allotropes.

Silicon is a metalloid, which means it has properties of both metals and nonmetals.

Scottish chemist Thomas Thomson named the element silicon in 1831, keeping part of the name Berzelius had given, but changing the ending of the name to -on because the element showed more similarities to boron and carbon than to the metals that had -ium names.

Berzelius is credited for the element's discovery because his sample was purified by repeatedly washing it, while earlier samples were impure. Gay-Lussac and Louis Jacques Thénard may have produced impure amorphous silicon in 1811. It's probable English scientist Humphry Davy may have isolated impure silicon in 1808 and French chemists Joseph L. The name derives from the Latin words silex or silicis, which mean "flint".

Credit for discovering silicon is given to Swedish chemist Jöns Jakob Berzelius, who reacted potassium fluorosilicate with potassium to produce amorphous silicon, which he named silicium, a name first proposed by Sir Humphry Davy in 1808.