Silicon

In 1789, the French chemist Antoine Lavoisier proposed that quartz (crystalline silicon dioxide) was likely to be the oxide of an element which was very common but not yet identified or isolated. ⁽¹⁾

It is possible that in England in 1808 Humphry Davy isolated partly pure silicon for the first time, but he did not realize it. ⁽²⁾

In 1811, French chemists Joseph L. Gay-Lussac and Louis Jacques Thénard may also have made impure silicon by reacting potassium with what we would now call silicon tetrafluoride to produce a reddish brown solid which was probably amorphous silicon. They did not, however, attempt to purify the new substance they had made. ^{(3), (4)}

In 1824 Swedish chemist Jöns Jakob Berzelius produced a sample of amorphous silicon, a brown solid, by reacting potassium fluorosilicate with potassium, purifying the product with repeated washing. He named the new element silicium. ^{(3), (4)}

At that time, the concept of semiconductors lay a century in the future and scientists debated whether the new element was a metal or nonmetal. Berzelius believed it was a metal while Humphry Davy thought it was a nonmetal. ⁽⁵⁾   The problem was that the new element was a better conductor of electricity than nonmetals, but not as good a conductor as a metal should be.

Silicon was given its name in 1831 by Scottish chemist Thomas Thomson. He retained part of Berzelius's name, from 'silicis', meaning flint. He changed the element's ending to on because the element was more similar to nonmetals boron and carbon than it was to metals such as calcium and magnesium. (Silicis, or flint, of course, was probably our first use of silicon dioxide. ^{(4), (6)}.)

In 1854 Henri Deville produced crystalline silicon for the first time using an electrolytic method. He electrolyzed an impure melt of sodium aluminum chloride to produce aluminum silicide. The aluminum was removed with water, leaving silicon crystals. ⁽⁴⁾

Silicon is not known to be toxic, but if breathed in as a fine silica/silicate dust it may cause chronic respiratory problems. Silicates such as asbestos are carcinogenic.

Silicon is a hard, relatively inert metalloid and in crystalline form is very brittle with a marked metallic luster. 

Silicon occurs mainly in nature as the oxide and as silicates.

The solid form of silicon does not react with oxygen, water and most acids. Silicon reacts with halogens or dilute alkalis.

Silicon also has the unusual property that (like water) it expands as it freezes. Four other elements expand when they freeze; gallium, bismuth, antimony and germanium

Silicon chips are the basis of modern electronic and computing. The silicon must be ultrapure, although depending on final use it may be doped with part per million levels of arsenic, boron, gallium, germanium, or phosphorus.

Silicon is alloyed with aluminum for use in engines as the presence of silicon improves the metal's castability. Silicon can enhance iron's magnetic properties is it is also an important component of steel, which it toughens.

Silicon carbide, more commonly called carborundum, is extremely hard and is used in abrasives.

Silica (SiO₂) in sand and minerals in clay is used to make concrete and bricks. Silica, as sand, is also the main constituent of glass.

Pure, crystalline silicon dioxide (quartz) resonates at a very precise frequency and is used in high-precision watches and clocks.

Silicones are important silicon based polymers. Having heat-resistant, nonstick, and rubber-like properties, silicones are often used in cookware, medicine (implants), and as sealants, adhesives, lubricants, and for insulation.

Silicon is the second most abundant element in Earth's crust, after oxygen and the eighth most abundant in the Universe. It is most commonly found as silicon dioxide (silica). Two elements, silicon and oxygen, make up almost three-quarters of our planet's crust. Commercial quantities of silicon are obtained by the reaction of silicon dioxide and carbon in an electric furnace using carbon electrod

Silicon has 14 isotopes whose half-lives are known, with mass numbers 22 to 36. Of these, three are stable: ²⁸Si, ²⁹Si and ³⁰Si.

References
1. R.W. Cahn, Silicon: Child and Progenitor of Revolution., Into The Nano Era, Springer Series in Materials Science, Volume 106. (2009) p3.
2. Thomas Edward Thorpe, Humphry Davy, Poet and Philosopher., (1896).
3. Mary Elvira Weeks, Discovery of the Elements., (2003) p162, Kessinger Publishing Reprints.
4. John Emsley, Nature's Building Blocks: An A-Z Guide to the Elements., (2002) p387. Oxford University Press.
5. H. R. Huff, U. Gösele, H. Tsuya, Semiconductor Silicon., (1998) p70, The Electrochemical Society.
6. Keith B. Hutton, Chemistry. (2001) p224. Routledge.