A LITTLE LIGHTBULB MOMENT
Organic chemistry: structure and stereochemistry
Stereoisomers
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Same wiring, different 3D arrangement
The idea behind the cue
Stereoisomers have the same molecular formula and the same connectivity, but differ in how atoms are arranged in space. Enantiomers and diastereomers are the two main stereoisomer classes.
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Short & simple
Same wiring, different 3D arrangement
Acronym
SS — Sparkly Squirrels.
Story
Two identical LEGO houses have the same bricks and connections. One faces north and one faces east. Nothing is rewired, but their shapes in space are not the same.
Connect the pieces
- S (Sparkly) → Same: Stereoisomers have the same molecular formula and the same connectivity.
- S (Squirrels) → Space: They differ only in how the atoms are arranged in 3D space, such as enantiomers and diastereomers.
- Sparkly · Same: Stereoisomers have the same molecular formula and the same connectivity.
- Squirrels · Space: They differ only in how the atoms are arranged in 3D space, such as enantiomers and diastereomers.
Know the limits
Does not include constitutional isomers, which differ in connectivity.
Further reading · OpenStax science and mathematics textbooks ↗Check your understanding
What distinguishes stereoisomers from constitutional isomers?
A. Different atom connectivity
B. Different molecular formula
C. Different 3D arrangement with same connectivity
D. Different numbers of atoms
Reveal explanation
Different 3D arrangement with same connectivity
Stereoisomers preserve connectivity but differ in spatial arrangement.