Isomers Flashcards
What are isomers?
Compounds that have the same molecular formula but a different arrangement of atoms.
What are structural isomers?
Compounds that have the same molecular formula but different structural formulae.
What are the three types of structural isomerism?
- Functional group isomerism
- Positional isomerism
- Branched chain isomerism
What causes functional group isomerism?
Different functional groups result in the same molecular formula.
Give examples of homologous series that can be functional group isomers.
- Alkenes and cycloalkanes
- Alcohols and ethers
- Aldehydes and ketones
What is positional isomerism?
Isomers that arise from differences in the position of a functional group in each isomer.
What is the primary alcohol butan-1-ol’s functional group position?
Attached to carbon-1.
What is the secondary alcohol butan-2-ol’s functional group position?
Attached to carbon-2.
What is branched chain isomerism?
When compounds have the same molecular formula, but their longest hydrocarbon chain is not the same.
How are amines classified?
Based on the number of alkyl groups attached to the nitrogen in the amine.
Define primary amines.
Amines where the nitrogen is attached to one other carbon atom.
Define secondary amines.
Amines where the nitrogen is attached to two other carbon atoms.
Define tertiary amines.
Amines where the nitrogen is attached to three other carbon atoms.
What are stereoisomers?
Isomers that have the same order of atoms but different spatial arrangements.
What are conformational isomers?
Isomers that occur due to free rotation about a single σ-bond.
What is a staggered conformer?
A conformer where hydrogen atoms on adjacent carbons have angles of 60 degrees.
Why is the eclipsed conformer less stable?
Due to repulsion between the electrons in the C-H bonds that are closer together.
What is configurational isomerism?
Isomerism seen in unsaturated compounds or compounds with at least one asymmetric carbon.
What are cis/trans isomers?
Isomers that differ in the position of functional groups relative to a double bond or ring.
What are the characteristics of cis isomers?
Functional groups are on the same side of the double bond or carbon ring.
What are trans isomers?
Functional groups are on opposite sides of the double bond or carbon ring.
What is a racemic mixture?
A mixture containing equal amounts of each enantiomer.
Why is a racemic mixture optically inactive?
The enantiomers cancel out each other’s effect on polarized light.
What is an enantiomer?
A pair of optical isomers that are mirror images of each other.
