Easy Trick to Remember Chiral vs Achiral Molecules
Hand Trick (Best Memory Aid)
Look at your left and right hands.
- They are mirror images of each other.
- But you cannot superimpose one on the other perfectly.
This is exactly what a chiral molecule is.
Chiral = Like Hands
- Mirror image exists.
- Mirror image cannot be superimposed.
- Often contains a carbon attached to four different groups.
Example:
- Lactic acid
- 2-Butanol
- Amino acids (except glycine)
🪞 Mirror Trick
Ask two questions:
- Does the molecule have a mirror image?
- Every molecule does.
- Can the molecule and its mirror image be perfectly overlapped?
- Yes → Achiral
- No → Chiral
🔍 Symmetry Rule (Most Useful in Exams)
If a molecule has an internal plane of symmetry → Achiral
If it lacks a plane of symmetry → Usually Chiral
Example:
Achiral/Chiral

Has a plane of symmetry → Achiral
Four different groups attached → Chiral
Quick Exam Shortcut
For carbon atoms:
Four Different Groups = Chiral Carbon
Examples to Memorize
| Molecule | Chiral/Achiral |
|---|---|
| Methane (CH₄) | Achiral |
| Ethane (C₂H₆) | Achiral |
| 2-Butanol | Chiral |
| Lactic Acid | Chiral |
| Glycine | Achiral |
| meso-Tartaric Acid | Achiral (due to symmetry) |
Golden Rule:
👉 “No symmetry + four different groups on carbon = Chiral.”
👉 “Plane of symmetry present = Achiral.”