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organic chemistry |
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| The chemistry of the element carbon, traditionally excluding the oxides and carbonates. Humans are carbon-based lifeforms, and as such we elevate carbon to a unique place among the elements. Of the six million compounds known, five million are organic. The division of all compounds into two classes, organic chemistry and everything else (See inorganic chemistry), is arbitrary and artificial (See organometallic chemistry). Carbon is unique for two main reasons. First, long chains can be built up. Although sulphur atoms, for example, also build long chains of up to about 500 000 atoms, these chains cannot be complex as sulphur forms only two bonds. Carbon can form two more bonds having made a chain, hence allowing enormous variation in the side chains. Second, carbon is at the top of Group 14 of the periodic table and so is the smallest atom in the group. Carbon atoms can therefore make stronger bonds than silicon atoms can. The higher bond strength means that carbon compounds are much more stable kinetically than the corresponding silicon compounds. The most important division within organic chemistry is into aromatic chemistry, based around rings such as those in benzene, and aliphatic chemistry, where molecules do not have benzene rings. Within each of these, further subdivision is possible, depending on the functional group(s) present. Examples of the resulting classes include alcohols, alkanes, alkenes and halogenoalkanes. |
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