Silicon the semiconductor
Impure silicon had already been obtained in Crystalline elemental silicon was not prepared until , when it was obtained as a product of electrolysis. In the form of rock crystal , however, silicon was familiar to the predynastic Egyptians, who used it for beads and small vases; to the early Chinese; and probably to many others of the ancients. The manufacture of glass containing silica was carried out both by the Egyptians—at least as early as bce —and by the Phoenicians.
Certainly, many of the naturally occurring compounds called silicates were used in various kinds of mortar for construction of dwellings by the earliest people.
Chemistry in its element: silicon
On a weight basis, the abundance of silicon in the crust of Earth is exceeded only by oxygen. Estimates of the cosmic abundance of other elements often are cited in terms of the number of their atoms per 10 6 atoms of silicon. Only hydrogen, helium , oxygen, neon , nitrogen , and carbon exceed silicon in cosmic abundance. Silicon is believed to be a cosmic product of alpha-particle absorption, at a temperature of about 10 9 K , by the nuclei of carbon, oxygen, and neon The energy binding the particles that form the nucleus of silicon is about 8.
Compared with the maximum of about 8. Pure silicon is too reactive to be found in nature, but it is found in practically all rocks as well as in sand , clays, and soils, combined either with oxygen as silica SiO 2 , silicon dioxide or with oxygen and other elements e. Its compounds also occur in all natural waters, in the atmosphere as siliceous dust , in many plants, and in the skeletons, tissues, and body fluids of some animals.
In compounds, silicon dioxide occurs both in crystalline minerals e. The natural silicates are characterized by their abundance, wide distribution, and structural and compositional complexities. These elements are said to be lithophilic, or stone-loving. Important silicate minerals include the clays, feldspar , olivine, pyroxene , amphiboles, micas, and zeolites.
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Jump to main content. Periodic Table. Glossary Allotropes Some elements exist in several different structural forms, called allotropes. Allotropes amorphous Si, crystalline Si. Glossary Group A vertical column in the periodic table. Fact box. Glossary Image explanation Murray Robertson is the artist behind the images which make up Visual Elements. Appearance The description of the element in its natural form.
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Biological role The role of the element in humans, animals and plants. Natural abundance Where the element is most commonly found in nature, and how it is sourced commercially. Uses and properties. Image explanation. The image is based on a diatom. Diatoms are photosynthesising algae. They are unique in that their cell walls are made of silica hydrated silicon dioxide. The element, when ultrapure, is a solid with a blue-grey metallic sheen. Silicon is one of the most useful elements to mankind.
Most is used to make alloys including aluminium-silicon and ferro-silicon iron-silicon. These are used to make dynamo and transformer plates, engine blocks, cylinder heads and machine tools and to deoxidise steel. Silicon is also used to make silicones. These are silicon-oxygen polymers with methyl groups attached.
Silicone oil is a lubricant and is added to some cosmetics and hair conditioners. Silicone rubber is used as a waterproof sealant in bathrooms and around windows, pipes and roofs. The element silicon is used extensively as a semiconductor in solid-state devices in the computer and microelectronics industries. For this, hyperpure silicon is needed.
The silicon is selectively doped with tiny amounts of boron, gallium, phosphorus or arsenic to control its electrical properties. Granite and most other rocks are complex silicates, and these are used for civil engineering projects. Sand silicon dioxide or silica and clay aluminium silicate are used to make concrete and cement. Sand is also the principal ingredient of glass, which has thousands of uses.
Silicon, as silicate, is present in pottery, enamels and high-temperature ceramics. Biological role. Silicon is essential to plant life but its use in animal cells is uncertain. Phytoliths are tiny particles of silica that form within some plants. Since these particles do not rot they remain in fossils and provide us with useful evolutionary evidence.
Silicon is non-toxic but some silicates, such as asbestos, are carcinogenic. Workers, such as miners and stonecutters, who are exposed to siliceous dust can develop a serious lung disease called silicosis. Natural abundance. Silicon makes up It does not occur uncombined in nature but occurs chiefly as the oxide silica and as silicates. The oxide includes sand, quartz, rock crystal, amethyst, agate, flint and opal.
The silicate form includes asbestos, granite, hornblende, feldspar, clay and mica. Elemental silicon is produced commercially by reducing sand with carbon in an electric furnace. High-purity silicon, for the electronics industry, is prepared by the thermal decomposition of ultra-pure trichlorosilane, followed by recrystallisation.
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Elements and Periodic Table History. Silica SiO 2 in the form of sharp flints were among the first tools made by humans. The ancient civilizations used other forms of silica such as rock crystal, and knew how to turn sand into glass. Attempts to reduce silica to its components by electrolysis had failed.
The product was contaminated with potassium silicide, but he removed this by stirring it with water, with which it reacts, and thereby obtained relatively pure silicon powder. Atomic data. Bond enthalpies. Glossary Common oxidation states The oxidation state of an atom is a measure of the degree of oxidation of an atom. Oxidation states and isotopes.
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Glossary Data for this section been provided by the British Geological Survey. Relative supply risk An integrated supply risk index from 1 very low risk to 10 very high risk. Recycling rate The percentage of a commodity which is recycled. Substitutability The availability of suitable substitutes for a given commodity. Reserve distribution The percentage of the world reserves located in the country with the largest reserves. Political stability of top producer A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.
Political stability of top reserve holder A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. Supply risk. Young's modulus A measure of the stiffness of a substance. Shear modulus A measure of how difficult it is to deform a material. Bulk modulus A measure of how difficult it is to compress a substance. Vapour pressure A measure of the propensity of a substance to evaporate.
Pressure and temperature data — advanced. Listen to Silicon Podcast Transcript :. You're listening to Chemistry in its element brought to you by Chemistry World , the magazine of the Royal Society of Chemistry. For this week's element we enter the world of science fiction to explore life in outer space.
Here's Andrea Sella. When I was about 12, my friends and I went through a phase of reading science fiction. There the were the fantastic worlds of Isaac Asimov, Larry Niven and Robert Heinlein, involving impossible adventures on mysterious planets - the successes of the Apollo space programme at the time only helped us suspend our disbelief.
One of the themes I remember from these stories was the idea that alien life forms, often based around the element silicon, abounded elsewhere in the universe. Why silicon? Well, it is often said that elements close to each other in the periodic table share similar properties and so, seduced by the age-old red herring that "carbon is the element of life", the writers selected the element below it, silicon.
Fullerene chemistry with silicon
I was reminded of these readings a couple of weeks ago when I went to see an exhibition of work by a couple of friends of mine. Called "Stone Hole" it consisted of stunning panoramic photographs taken at extremely high resolution inside sea caves in Cornwall. As we wandered through the gallery a thought occurred to me. Silicate rocks - those in which silicon is surrounded tetrahedrally by four oxygen atoms - exist in an astonishing variety, the differences being determined by how the tetrahedra building blocks link together, and what other elements are present to complete the picture.
When the tetrahedra link one to the next, one gets a mad tangle of chains looking like an enormous pot of spaghetti - the sorts of structures one gets in ordinary glass. The purest of these chain-like materials is silicon dioxide - silica - found quite commonly in nature as the colourless mineral quartz or rock crystal. In good, crystalline quartz, the chains are arranged in beautiful helices and these can all spiral to the left. Or to the right. When this happens the crystals that result are exact mirror images of each other. But not superimposable - like left and right shoes.
To a chemist, these crystals are chiral, a property once thought to be the exclusive property of the element carbon, and chirality, in turn, was imagined to be a fundamental feature of life itself. Yet here it is, in the cold, inorganic world of silicon. Most grandiose of all, one can make porous 3D structures - a bit like molecular honeycombs - particularly in the presence of other tetrahedral linkers based on aluminium. These spectacular materials are called the zeolites, or molecular sieves.