Silicon is a chemical element, having the chemical symbol Si. Its atomic number (the number of protons) is 14. It has a standard atomic weight of 28.0855 g•mol −1, and is typically found as a solid in its various forms as silicon dioxide, silica and silicates.
Silicon is considered a member of the "Metalloid" class of element. At a pressure of 101.325 kPa, it has a boiling point 3,265 °C, and a melting point of 1,414 °C. In Earth's crust, silicon is the second most abundant element after oxygen, being about 28% of the crust by mass.