Isomers are compounds that have the same molecular formula (same number and types of atoms) but different arrangements of atoms, resulting in different properties.
Types of Isomers
- Structural (Constitutional) Isomers
- Atoms are connected in different ways.
- Types:
- Chain isomers – different arrangements of the carbon chain.
- Position isomers – functional group or substituent at different positions.
- Functional group isomers – same formula but different functional groups (e.g., alcohol vs ether).
- Stereoisomers
- Atoms are connected the same way but arranged differently in 3D space.
- Types:
- Geometrical isomers (cis/trans or E/Z) – due to restricted rotation around double bonds or rings.
- Optical isomers (enantiomers and diastereomers) – differ in chirality and mirror-image relationships.
Importance of Isomers
- They often have very different physical and chemical properties despite having the same formula.
- In biology and medicine, different isomers can have completely different effects (e.g., one isomer of a drug may be therapeutic, while another may be harmful).
In short: Isomers are like different “arrangements” of the same building blocks, giving rise to distinct compounds.