Silicon

Silicon is the chemical element of atomic number 14, symbol Si and atomic weight 28.085. In its crystalline form of dark gray crystals, it has a specific gravity of 2.42 at 68°F (20°C), a melting point of 2,588°F (1,420°C) and a boiling point 5,936°F (3,280°C). It exists also in an amorphous (shapeless) form, a brown powder. Silicon consists of three stable isotopes of mass numbers 28, 29 and 30.

Silicon, is a key component of microchips and microprocessors that allow the construction of inexpensive digital wristwatch to worldwide networks of computers. The conductive properties of silicon allow micro-devices to perform millions of calculations per second.

In terms of weight, silicon is the second most abundant element in the crust of Earth at 27.7%—second only to oxygen (46.6%). In rough terms, Earth is essentially a spheroid of iron (the core) surrounded by layers (the mantle and the crust) of silicon and oxygen dominated compounds that include the other elements.

Earth was originally a molten ball of mostly iron, oxygen, silicon and aluminum that cooled. While still molten lighter atoms—including silicon and oxygen (atomic weights 28 and 16), moved outward from the core region, while the heavier iron atoms (atomic weight 56) dominated the central core. By about 3.5 billion years ago, the outermost layer had cooled to a crustal surface. The crustal composition is three-quarters oxygen and silicon.