Molecules with the same molecular formula, but a different arrangement of atoms in space. This definition excludes different arrangements caused by the molecule rotating as a whole or rotating about specific bonds. For example, two views of butane show the same molecule because free rotation occurs around all carbon-carbon single bonds.
The Lego Blocks of Chemistry
- Core idea: Isomers are like different shapes built from the exact same set of toy blocks.
- The rule: If you only twist or turn the whole toy without taking it apart, it is still the same shape.
- The test: You must take the pieces apart and build a new shape to make a true isomer.
Understanding With Models
- Use physical models: Real models make isomerism much easier to learn.
- Buy a cheap set: Sets like Molymod work very well for organic chemistry.
- Build your own: Colored modeling clay and used matches also work if you want a budget option.