4.1 Stereoisomerism Flashcards
What are structural isomers?
Molecules which have the same molecular formula but different structural formulae
What are stereoisomers?
Molecules that have the same molecular and structural formula but a different spatial arrangement atoms
Examples of stereoisomerism
E-Z isomers
Optical isomers
What are E-Z isomers?
Two molecules that have the same molecular and structural formula but their atoms have different spatial arrangement
What are optical isomers?
Two molecules that have the same 4 groups arranged around a central carbon atom, the groups are arranged different in space
What is a chiral centre
A central atom (carbon) that has 4 different groups bonded to it
What are enantiomers?
Two optical isomers that are non-superimposable mirror-image isomers
What is optical activity?
A solution that can rotate plane polarised light
What is a racemic mixture?
An equimolar mixture of both optical isomers
How to identify the chiral centre
Placing a star next to it
What does it mean that two optical isomers are non-superimposable
They are mirror images of eachother
What structure should optical isomers be drawn in?
Tetrahedral 3D structure
Note a physical property which two enantiomers have and which can be used to distinguish between them.
Enantiomers rotate the plane of vibration of plane polarised light in opposite directions
1 will rotate it clockwise
The other will rotate it anti-clockwise but to the same angle
