Silicon is a chemical element with symbol Si and atomic number 14. It is a tetravalent metalloid, more reactive than germanium, the metalloid directly below it in the periodic table. Controversy about silicon's character dates to its discovery. It was first prepared and characterized in pure form in 1823. In 1808, it was given the name silicium (from Latin: silex, hard stone or flint), with an -ium word-ending to suggest a metal, a name which the element retains in several languages. The present English name was first suggested in 1817 to conform with the physically similar elements, carbon and boron.
Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure free element in the Earth's crust. It is most widely distributed in dusts, sands, planetoids, and planets as various forms of silicon dioxide (silica) or silicates. Over 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust (about 28% by mass) after oxygen.
It is the second most common base element for Union lifeforms (after carbon).