Silicon

Silicon is a chemical element with the symbol Si. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid and semiconductor.

Silicon metal is a grey and lustrous semi-conductive metal that is used to manufacture steel, solar cells, and microchips.

Silicon is the second most abundant element in the earth's crust (behind only oxygen) and the eighth-most common element in the universe. Nearly 30 percent of the weight of the earth's crust can be attributed to silicon.

Like water - but unlike most metals - silicon contracts in its liquid state and expands as it solidifies. It has relatively high melting and boiling points, and when crystallized forms a diamond cubic crystal structure. Critical to silicon's role as a semiconductor and its use in electronics is the element's atomic structure, which includes four valence electrons that allow silicon to bond with other elements readily.