The name organic chemistry came from the word organism. Prior to 1828, all organic compounds had been obtained from organisms or their remains. The scientific philosophy back then was that the synthesis of organic compounds could only be produced within living matter while inorganic compounds were synthesized from non-living matter. A theory known as “Vitalism” stated that a “vital force” from living organisms was necessary to make an organic compound. 1828, a German chemist Friedrich Wöhler (1800-1882) amazed the sience community by using the inorganic compound ammonium cyanate, NH4OCN to synthesize urea, H2NCONH2, an organic substance found in the urine of many animals. This led to the disappearance of the “Vitalism” theory.

Today, chemists consider organic compounds to be those containing carbon and one or more other elements, most often hydrogen, oxygen, nitrogen, sulfur, or the halogens, but sometimes others as well. Organic chemistry is defined as the chemistry of carbon and its compounds.

The Uniqueness of Carbon

There are more carbon compounds than there are compounds of all other elements combined. Plastics, foods, textiles, and many other common substances contain carbon. With oxygen and a metallic element, carbon forms many important carbonates, such as calcium carbonate (limestone) and sodium carbonate (soda). Certain active metals react with it to make industrially important carbides, such as silicon carbide, an abrasive known as carborundum, and tungsten carbide, an extremely hard substance used for rock drills and metalworking tools.

The great number of carbon compounds is possible because of the ability of carbon to form strong covalent bonds to each other while also holding the atoms of other nonmetals strongly. Carbon atoms have the special property to bond with each other to form chains, ring, spheres, and tubes. Chains of carbon atoms can be thousands of atoms long, as in polyethylene.

Polyethylene chain:

H H H H H H H H H H H
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H-C-C-C-C-C-C-C-C-C-C-C-etc.
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H H H H H H H H H H H

Structural Isomers

Isomers are classified as structural isomers, which have the same number of atoms of each element in them and the same atomic weight but differ in the arrangement of atoms in the molecule. For example, there ware two compounds with the molecular formula C2H6O. One is ethanol (also called ethyl alcohol), CH3CH2OH, a colorless liquid alcohol; the other is dimethyl ether, CH3OCH3, a colorless gaseous ether. Among their different properties, ethanol has a boiling point of 78.5°C and a freezing point of -117°C; dimethyl ether has a boiling point of -25°C and a freezing point of -138°C. Ethanol and dimethyl ether are isomers because they differ in the way the atoms are joined together in their molecules.