Silicon: the essentials Brief description: silicon is present in the sun and stars and is a principal component of a class of meteorites known as aerolites. Silicon makes up 25.7% of the earth's crust by weight, and is the second most abundant element, exceeded only by oxygen. It is found largely as silicon oxides such as sand (silica), quartz, rock crystal, amethyst, agate, flint, jasper and opal. Silicon is found also in minerals such as asbestos, feldspar, clay and mica. Silicon is important in plant and animal life. Diatoms in both fresh and salt water extract silica from the water to use as a component of their cell walls. Silicon is an important ingredient in steel. Silicon carbide is one of the most important abrasives. Workers in environments where silicaceous dust is breathed may develop a serious lung disease known as silicosis.
Hydrolysis and condensation of substituted chlorosilanes can be used to produce a very great number of polymeric products, or silicones. These range from liquids to hard, glasslike solids with many useful properties. Elemental silicon transmits more than 95% of all wavelengths of infrared and and has been used in lasers to produce coherent light at 456 nm.
IsolationIsolation: there is normally no need to make silicon in the laboratory as it is readily available commercially. Silicon is readily available through the treatment of silica, SiO2, with pure graphite (as coke) in an electric furnace. SiO2 + 2C → Si + 2CO Under these conditions, silicon carbide, SiC, can form. However, provided the amount of SiO2 is kept high, silicon carbide may be eliminated. 2SiC + SiO2 → 3Si + 2CO Very pure silicon can be made by the reaction of SiCl4 with hydrogen, followed by zone refining of the resultant silicon. SiCl4 + 2H2 → Si + 4HCl WebElements ShopWebElements now has an online shop at which you can buy periodic table posters, mugs, T-shirts, games, molecular models, and more.
|
|||||||||
 
|
|
Silicon
Silicium
Silicium
Silicium
Silicio
Silicio
Kisel
Silício