Advanced Topics
In a nutshell: Stereochemistry studies the 3D arrangement of atoms, crucial in pharmaceuticals and biology.
## Looking at Molecules in 3D
Not all molecules with the same formula are identical—some are mirror images! This is the world of stereochemistry.
### Chirality
A molecule is chiral if it cannot be superimposed on its mirror image (like your hands). Chirality is crucial in nature and medicine.
### Enantiomers
- **Enantiomers** are pairs of chiral molecules that are mirror images.
- Their properties may be identical in most ways, but they often interact with living systems differently.
### Why Stereochemistry Matters
Many drugs work only if they have the correct 3D shape. One enantiomer might be a helpful medicine, while its mirror image could be ineffective or even harmful.
Examples
- The two enantiomers of limonene smell like oranges and lemons, respectively.
- Thalidomide's different enantiomers led to very different effects in patients.
Key terms
- Chirality
- A property where an object is not superimposable on its mirror image.
- Enantiomer
- One of a pair of molecules that are mirror images of each other.