Understanding Molecular Isomers:

Molecular isomers are fascinating compounds that share identical molecular formulas but exhibit different structural arrangements. In the HSC Chemistry curriculum, we explore three fundamental types of isomerism that help us understand how atoms can be organized in distinct ways while maintaining the same chemical composition.

What Are Isomers?

Isomers are compounds that have the same molecular formula but different structural arrangements of their atoms. This difference in structure leads to distinct chemical and physical properties. For HSC Chemistry, we focus on three main types of structural isomers:

Chain Isomers: Different Carbon Backbones

Chain isomers occur when compounds share the same molecular formula but have different arrangements of their carbon chain backbone. A classic example is found in compounds with the molecular formula C₅H₁₂:

Position Isomers: Same Group, Different Location

Position isomers maintain the same molecular formula and functional group but differ in where that functional group is located on the carbon chain. Consider butene (C₄H₈), which can exist as:

Functional Group Isomers: Different Chemical Features

Functional group isomers share a molecular formula but contain different functional groups entirely. Here are three important pairs of functional group isomers:

1. Alcohols and Ethers

Example: C₂H₆O can exist as:

2. Aldehydes and Ketones

Example: C₃H₆O can exist as:

3. Carboxylic Acids and Esters

Example: C₃H₆O₂ can exist as:

Practice Questions