Silicon

Silicon, chemical element, symbol Si; for physical constants see Periodic Table. Silicon was isolated by Jöns J. Berzelius in 1823. It occurs in nature as sand, quartz, granite, feldspar, asbestos, and many other minerals. It is the second most abundant element and makes up 25.7% of the earth's crust by weight. Silicon is prepared by heating silicon dioxide in an electric furnace, using carbon electrodes. Silicon is a gray, lustrous, unreactive metalloid. It can be amorphous or crystalline. Silicon transmits more than 95% of all wavelengths of infrared radiation. Single crystals of silicon are used for solid-state or semiconductor devices. Silicones, a class of compounds prepared by hydrolyzing organic chlorides, are numerous with hundreds of useful properties, especially in the form of pottery, glass, and building materials. Silicon and its compounds are used in steel, as abrasives, and in lasers.