How do you distinguish between different types of structural isomers?

Structural isomers are distinguished by differences in their physical properties, chemical properties, and the arrangement of their atoms.

Structural isomers, also known as constitutional isomers, are molecules with the same molecular formula but different structural formulas. This means they have the same number of atoms of each element, but these atoms are arranged differently. There are three main types of structural isomers: chain isomers, functional group isomers, and positional isomers.

Chain isomers have a different arrangement of the carbon skeleton. For example, butane and 2-methylpropane are chain isomers. They both have the molecular formula C4H10, but butane has a straight chain of four carbon atoms, while 2-methylpropane has a branched chain.

Functional group isomers have the same atoms arranged into different functional groups. A functional group is a group of atoms that determine the chemical behaviour of a compound. For instance, ethanol and dimethyl ether are functional group isomers. They both have the molecular formula C2H6O, but in ethanol, the oxygen atom is part of a hydroxyl group (-OH), while in dimethyl ether, it is part of an ether group (-O-).

Positional isomers have the same carbon skeleton and the same functional groups, but the functional groups are attached to different carbon atoms. For example, 1-propanol and 2-propanol are positional isomers. They both have the molecular formula C3H8O and contain a hydroxyl group, but in 1-propanol, the hydroxyl group is attached to the end carbon atom, while in 2-propanol, it is attached to the middle carbon atom.

In summary, structural isomers can be distinguished by their different physical properties (such as boiling point and melting point), different chemical properties, and the different arrangement of their atoms. Understanding these differences is crucial for predicting how these compounds will behave in chemical reactions.