<Tr> <Td_colspan="2"> <Ul> <Li> view </Li> <Li> talk </Li> <Li> </Li> </Ul> references in Wikidata </Td> </Tr> <Ul> <Li> view </Li> <Li> talk </Li> <Li> </Li> </Ul> <P> Silicon is a chemical element with symbol Si and atomic number 14 . It is a hard and brittle crystalline solid with a blue - grey metallic lustre; and it is a tetravalent metalloid and semiconductor . It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, and lead are below it . It is relatively unreactive . Because of its large chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form . Its melting and boiling points of 1414 ° C and 3265 ° C respectively are the second - highest among all the metalloids and nonmetals, being only surpassed by boron . Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure 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 . </P> <P> Most silicon is used commercially without being separated, and often with little processing of the natural minerals . Such use includes industrial construction with clays, silica sand, and stone . Silicates are used in Portland cement for mortar and stucco, and mixed with silica sand and gravel to make concrete for walkways, foundations, and roads . They are also used in whiteware ceramics such as porcelain, and in traditional quartz - based soda - lime glass and many other specialty glasses . Silicon compounds such as silicon carbide are used as abrasives and components of high - strength ceramics . Silicon is the basis of the widely used synthetic polymers called silicones . </P>

What group is silicon (si) in