A Level Chemistry : Isomers

Question 1

What are Structural Isomers?

Answer 1

Compounds with the same molecular formula but different structural formula

Question 2

What are the 3 different types of structural isomerism?

Answer 2

• Chain Isomerism
• Positional Isomerism
• Functional group isomerism

Question 3

What is Chain Isomerism?

Answer 3

• When compounds have the same molecular formula, but their longest hydrocarbon chain is not the same
• This is because of branching, eg. Pentane and 2,2-Dimethyl Propane

Question 4

What is positional Isomerism?

Answer 4

• Caused by the difference in position of a functional group of each isomer
• Functional group can be locked onto different carbons
• Eg. Butan - 1 - ol and butan - 2 - ol

Question 5

What is Functional Group isomerism?

Answer 5

• When different functional groups result in the same molecular formula
• Very different chemical properties, because there are different functional groups
• Eg. Butanol, ethoxyethane

Question 6

How to deduce all possible isomers

Answer 6

Step 1 - Draw the structural formula

Step 2 - Determine whether it is a stereo or a structural isomer

Step 3 - Determine whether it is a functional group, positional or chain isomer

Question 7

What is stereoisomerism?

Answer 7

Where there are isomers around a C=C double bond

Question 8

What is EZ Isomerism?

Answer 8

E isomers - have functional groups on opposite sides of the C=C bond

Z Isomers - Have functional groups on the same side of the C=C bond

Cis isomers - Same as a Z isomer

Trans isomers - Same as E isomers