Silicon is the second element in Group 14 of the periodic table. It has an atomic number of 14, an atomic mass of 28.0855, and a chemical symbol of Si

Properties

Silicon exists in two allotropic forms, one of which consists of shiny, grayish black needle-like or crystal plates. The other allotrope is an amorphous brown powder. The melting point of the crystalline allotrope is 2,570°F (1,410°C), its boiling point is 4,270°F (2,355°C), and its density is 2.33 grams per cubic centimeter. Silicon is a relatively hard element with a hardness of 7 on the Mohs scale. Silicon is a semiconductor, a property which determines some of its most important uses.

As its two allotropic forms might suggest, silicon is a metalloid. It is relatively inactive at room temperature, and resists attack by water and most acids. At higher temperatures, it reacts with many metals, oxygen, nitrogen, sulfur, phosphorus...