All practice pages/Interatomic theory/Elements
Element 14, a metalloid
The second most abundant element in the crust, the main ingredient of sand and rock, and the element computer chips are made from.
Period 3, group 14. The other metalloids are tinted, and every cell opens its own article.
Silicon has 14 electrons, one for every proton, so the atom carries no charge. Below are the same 14 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p²
Short form: [Ne] 3s² 3p², where [Ne] stands for the 10 electrons neon already has.
The simple form counts electrons shell by shell. The orbital form says which subshell each one sits in: s holds 2, p holds 6, d holds 10 and f holds 14. Shell 2 here is 2s² 2p⁶, and 2 + 6 is 8.
Silicon sits in period 3 and has 3 shells. The period number counts the shells.
The outer shell holds 4 electrons. Those are the ones silicon can lose, gain or share, so they are the ones that decide what it bonds with. For a main-group element the group number gives that count: group 14 means 4.
Four valence electrons like carbon, so silicon forms four covalent bonds. Unlike carbon it rarely bonds to itself in long chains; instead it links through oxygen, Si-O-Si, in quartz, glass and the silicate minerals.
About 28% of the crust by mass, second only to oxygen, but never free: it is in quartz sand, clay, granite and nearly every rock-forming mineral, bound to oxygen.
Jöns Jacob Berzelius isolated it in 1824 by heating potassium fluorosilicate with potassium. The name comes from the Latin silex, flint, with the ending -on to match carbon and boron.
Ultra-pure silicon is the base of computer chips and most solar panels. Far more is used as sand and silicates in concrete, glass and ceramics. Silicon metal strengthens aluminum alloys, and silicones, polymers with a silicon-oxygen backbone, make sealants, bakeware, lubricants and medical implants.