Isomers
Definition and meaning of Isomers in chemistry.
Isomers are compounds that have the same molecular formula but a different arrangement of atoms, resulting in distinct structures. Because of these structural differences, isomers typically have different physical and chemical properties.
In more detail
The key to understanding isomers is recognizing that molecular formula alone does not determine a compound's identity or behavior. Two molecules could have identical element counts yet exhibit vastly different melting points, boiling points, reactivity, and biological activity. The two major categories are structural (constitutional) isomers, which differ in how atoms are bonded to each other, and stereoisomers, which have the same connectivity but differ in spatial orientation in three-dimensional space. This concept is crucial in chemistry because it explains why formula alone cannot predict a substance's properties.
Key facts
| Definition | Same molecular formula, different atomic arrangement |
|---|---|
| Main types | Structural (constitutional) isomers and stereoisomers |
| Common example | C2H6O (ethanol and dimethyl ether) |
| Field | Organic Chemistry |
Ethanol (C2H6O) and dimethyl ether (C2H6O) are isomers: both have the same molecular formula but different structures. Ethanol is a liquid with a boiling point of 78°C, while dimethyl ether is a gas that boils at −24°C.
Frequently asked questions
Can isomers be separated?
Yes. Because isomers have different physical properties like boiling points, melting points, and solubility, they can be separated by distillation, crystallization, or chromatography.
Do isomers have the same reactivity?
No. While isomers share the same molecular formula, their different structures result in different chemical reactivity and biological activity.