Isomerism and isomers

Isomerism and Isomers

Isomerism is the phenomenon whereby certain compounds, with the same molecular formula, exist in different forms owing to their different organisations of atoms. The concept of isomerism illustrates the fundamental importance of molecular structure and shape in organic chemistry.

Structural isomerism
When the isomers differ only in the arrangement of atoms or groups within the molecule, without any reference to space, these are known as structural isomers
and the phenomenon as
structural isomerism.
Thus the structural isomers have the same molecular formula, but possess different structural formulae. Structural isomerism may again be of several types.

Alkanes with more than three carbon atoms can be arranged in numerous different ways, forming different structural isomers. An isomer is like a chemical anagram, in which the atoms of a chemical compound are arranged or joined together in a different order. The simplest isomer of an alkane is the one in which the carbon atoms are arranged in a single chain with no branches. This isomer is sometimes called the n-isomer (n for "normal", although it is not necessarily the most common). However the chain of carbon atoms may also be branched at one or more points. The number of possible isomers increases rapidly with the number of carbon atoms
CH4 (0 isomers)C4H10 (2 isomers)
C2H6(0 isomers)
C3H8(0 isomers)
C5H12 (3 isomers)
C6H14 (5 isomers)
C7H16 (9 isomers)
C8H18 (18 isomers)
C9H20 (35 isomers)
C10H22 (75 isomers)
C11H24 (159 Isomers)
C12H26  (355 Isomers)
C13H28  (802 Isomers)
C14H30  (1,858 Isomers)