Structural Isomerism in Alkenes

In alkenes, as with alkanes, a difference in the carbon skeleton or the location of a substituent may cause isomerism. For example, 

Additionally in alkenes, the C = C double bond may be between different carbon atoms in the carbon chain. This kind of arrangement would form a new compound with the same number of carbon and hydrogen atoms. In ethene and propene, there is only one possibility for the location of the C = C double bond. But in butene (C4Hg) there are two possibilities  

The only difference between 1-butene and 2-butene is the location of C = C double bond. 

Both alkenes and cycloalkanes have the same general formula, Therefore 

Structural isomers have the same molecular formula, but their structural formulae are different, and this leads to different physical and chemical properties. For example, C Hjq has five isomers and all of them have different boiling points. 

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