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Toxic_Kisses
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Symbol Si, is a nonmetallic element of great importance to man. Present in stars and meteorites, it constitutes about 27.6% of the earth’s crust by weight and is the second most abundant element on earth, after oxygen. It is found in animal skeletons and plant tissues and forms the cell walls of diatoms. The element does not occur naturally on earth in the free state. It was first isolated by the English chemist Sir Humphry Davy in 1800 and the French chemists Louis Thenard and Joseph Gay-Lussac in 1811, but was not identified as an element until 1826 by the Swedish chemist Jakob Berzelius. Crystalline silicon was first prepared by the French chemist Henri Sainte-Claire Deville in 1854.
Properties. Located in Group IVA of the periodic table, silicon is one of the carbon family of elements. Its atomic number is 14 and its atomic weight 28.086. In its crystalline form it is a black to dark gray, brittle solid with a high metallic luster. In its amorphous form it is dark brown. The element has a specific gravity of 2.33 and it is one of the harder solids, with a hardness of 7 on the Mohs scale. Silicon melts at 1410’ C (2570’ F) and boils at 2355’ C (4271’ F). Silicon is a poor conductor of electricity and it expands very little when it is heated.
Silicon has a valence of +4. It is not a reactive element. Practically insoluble in water, it is unaffected by most acids except hydrofluoric acid. However, it combines with the halogens and reacts with alkalis, even in diluted solutions, to form silicates and hydrogen. Its affinity for hydrogen is weak, compared to that of carbon, and in nature the element is found mainly in combination with oxygen.
Preparation and Uses. Although silicon can be prepared in several ways, it is generally made commercially by heating the dioxide, silica (Si02), with coke in an electric furnace. Zone refining of the element yields very high-purity silicon, as does decomposition of silicon tetraiodide (SiI4) and trichlorosilane (SiHCl3). High-purity silicon is of great importance in the electronics industries. Doped with elements such as boron, gallium, phosphorus, and arsenic, it is used in making transistors, silicon diodes, and other semiconductors.
Silicon of ordinary purity is used in alloys, which the element forms with most metals. Such alloys include ferrosilicon, used in making very resistant silicon steels and metallic magnesium, and silicon copper, combined with tin to make the silicon bronze used in telephone and telegraph wires. The element is also combined with certain ceramic materials to make cermets and other special refractories, and it serves as a reducing agent of metallic oxides in some high-temperature reactions.
Compounds. Silicon occurs in the form of silica and silicates in rocks and in minerals such as sands, clays, and feldspars, to name a very few of these, important natural compounds. In fact, the earth’s crust may be thought of as essentially a network of silicon and oxygen atoms. Among the many silicon compounds in commercial use are the silanes and their derivatives, such as monosilane (SiH4) and disilane (Si2H6), and the organic polymers called silicones. Sodium silicate is better known as water glass, and silicon carbide is valued for its hardness.
Silicpon is capable of forming some of the long-chain molecules needed in any process as complex as life, but it has not achieved a life of its own. It may be a sleeper in this regard, however. Carbon’s principal products, living organisms, have struggled over a few billion years to establish mechanisms for the accumulation and dispersal of information (an austere distillation and definition of what we mean by “life”), and silicon has lain in wait. The recent alliance of the two regions, in which carbon-based organisms have developed the use of silicon-based artifacts for information technology, has resulted in the enslavement of silicon. However, such is the precocity of carbon’s organisms that they are steadily developing silicon’s latent powers, and one day silicon may well assume the dominant role. It certainly has long-term potential, for its metabolism and replication need not be as messy as carbon’s. Silicon will not realize its potential without the burden of development being carried out by carbon.
Silicon and its northern and western neighbors oxygen and aluminum formed the silicates and aluminosilicates—the rocks we currently stand on—and these light elements floated on the denser elements, like iron and nickel, that sank to the planet’s molten depths, where they still lie.
Metalloids, possess metallic and nonmetallic characteristics. This diagonal zone includes familiar regions, like silicon and arsenic, and some regions perhaps less familiar, like antimony and polonium. It is to be noted that carbon abuts this zone and that silicon lies within it. It is probably no coincidence that this ambiguous territory includes the elements that make possible the most complex properties of all, life and consciousness.
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A report I did for school a few years back, just stumbled onto it in word and thought, why not?
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