Notice that isobutane has the same molecular formula, C4H10, as n-butane but has a different structural formula. Two different molecules which have the same molecular formula are isomers. Isomers which differ in the connectivity of bonds are constitutional isomers, or structural isomers.
Similarly one may ask, what is the meaning of isomerism in alkanes?
Isomerism is the existence of two or more compounds with the same molecular formula (i.e. containing the same elements combined in the same proportion by mass), but different molecular structures. Alkanes exhibit structural isomerism because of the possibility of branching of the carbon chains.
Beside above, why do alkanes form isomers? This makes isomers of non-substituted alkanes impossible because the atoms can shift back and forth. Pi bonds, like those in double bonds, can't freely move around. Since each carbon in a double-bond chain can form another bond that doesn't move, you can create symmetrical isomers.
In respect to this, what are isomers of alkenes?
Using butene as an example, there are four isomers for the alkene (1-butene, cis-2-butene, trans-2-butene, and isobutene), whereas there are only two for the corresponding alkane (n-butane and isobutane).
Which are isomers?
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulas — that is, same number of atoms of each element — but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties.
