Alkanes
In organic chemistry, an alkane, or paraffin (a historical name that also has ), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon-carbon bonds are single. Alkanes have the general chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, CH4 where n = 1 (sometimes called the parent molecule), to arbitrarily large molecules.
Besides this standard definition by the International Union of Pure and Applied Chemistry, in some authors' usage the term alkane is applied to any saturated hydrocarbon, including those that are either monocyclic (i.e. the cycloalkanes) or polycyclic.
In an alkane, each carbon atom has 4 bonds (either C-C or C-H), and each hydrogen atom is joined to one of the carbon atoms (so in a C-H bond). The longest series of linked carbon atoms in a molecule is known as its carbon skeleton or carbon backbone. The number of carbon atoms may be thought of as the size of the alkane.
One group of the higher alkanes are waxes, solids at standard ambient temperature and pressure (SATP), for which the number of carbons in the carbon backbone is greater than about 17.
With their repeated -CH2- units, the alkanes constitute a homologous series of organic compounds in which the members differ in molecular mass by multiples of 14.03 u (the total mass of each such methylene-bridge unit, which comprises a single carbon atom of mass 12.01 u and two hydrogen atoms of mass ~1.01 u each).
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