Silicon

 (Latin: silicium) is the chemical element in the periodic table that has the symbol Si and atomic number 14.

A tetravalent metalloid, silicon is less reactive than its chemical analog carbon. It is the second most abundant element in the Earth's crust, making up 25.7% of it by weight. It occurs in clay, feldspar, granite, quartz and sand, mainly in the form of silicon dioxide (also known as silica) and as silicates, (various compounds containing silicon, oxygen and one or another metal). Silicon is the principal component of most semiconductor devices and, in the form of siliica and silicates, in glass, cement, ceramics. It is also a component of silicones, a name for various plastic substances often confused with silicon itself. Silicon is widely used in semiconductors because it has a lower reverse leakage current than the semiconductor Germanium, and because its native oxide is easily grown in a furnace and forms a better semiconductor/dielectric interface than almost all other material combinations.

Notable characteristics:In its crystalline form, silicon has a dark gray color and a metallic luster. Even though it is a relatively inert element, silicon still reacts with halogens and dilute alkalis, but most acids (except for a combination of nitric acid and hydrofluoric acid) do not affect it. Elemental silicon transmits more than 95% of all wavelengths of infrared light. Pure silicon has a negative temperature co-efficient of resistance, since the number of free charge carriers increases with temperature. The electrical resistance of single crystal silicon significantly changes under the application of mechanical stress due to the piezoresistive effect.

Applications:Silicon is a very useful element that is vital to many human industries.

Silicon and alloys: