isomerism in organic molecules

Question 1

structural isomers

Answer 1

• differ in their bonding sequence/molecular skeleton

- usually different compounds with different physical and chemical properties

Question 2

types of structural isomers

Answer 2

• chain or skeletal isomerism
• position isomerism
• functional group isomerism
• tautomerism - movement of bonds and proton

Question 3

stereoisomers

Answer 3

same structural formula but different 3-D arrangement of atoms in space
- geometric isomerism
optical isomerism

Question 4

optical isomers

Answer 4

ability to rotate plane-polarised light in opposite directions
- requires chiral centre
compounds with more than one chiral centre may not show optical activity depending on whether or not they are non-superimposable on their mirror image (chiral) or superimposable (achiral)

Question 5

enantiomers

Answer 5

• the non superimposable mirror image forms of a chiral molecules are called enantiomers
• have identical physical properties in all respects except in their interaction with plane of polarised light

Question 6

racemic mixtures

Answer 6

a 1:1 mixture of the two enantiomers of a compound is known as a racemic mixture

Question 7

diastereomers

Answer 7

a structure with n chiral centres has 2n possible isomers

- diastereomers that differ at only one carbon are called epimers

Question 8

important of enantiomers

Answer 8

proteins/receptors/enzymes made up of L-amino acids = chiral environment - differentiates between isomers