Silicium

Silicium is the chemical element with symbol Si and atomic number 14. It is a metalloid and the second most abundant element in Earth's crust, after oxygen, comprising about 28% by mass. In the universe, silicium is relatively common as a product of stellar nucleosynthesis.

In nature silicium is not found free in significant quantities; it occurs mainly as silica (SiO2) and as silicate minerals. Industrial production of elemental silicium begins with reduction of silica or quartz with carbon, typically in an electric arc furnace, to produce metallurgical-grade silicium. Purification to semiconductor-grade or solar-grade involves multiple steps such as chemical purification and distillation, with common processes including the Siemens process.

Silicium is a hard, brittle solid with a high melting point (1414°C) and a very high boiling point (about 2900°C). It crystallizes in a diamond cubic lattice and possesses a band gap of about 1.12 eV at room temperature, giving it semiconducting properties. In its pure form it is a poor conductor, but conductivity can be controlled by doping with elements such as phosphorus or boron.

Natural silicium consists of three stable isotopes: 28Si (~92.2%), 29Si (~4.7%), and 30Si (~3.1%). The abundance is relevant for scientific use and isotopic labeling.

The element was isolated in the early 19th century by Jöns Jakob Berzelius; the older name silicium is still used in some languages, while silicon is the IUPAC preferred name. Applications include electronics and photovoltaics; silicium is a key component of computer chips and solar cells, and the element forms a wide range of materials including silicones.