Structural and Stereoisomers

Question 1

What are chain isomers?

Answer 1

Molecules that have different arrangements of the carbon skeleton.
They have similar chemical properties- but their physical properties will be different because of the change in shape of the molecule.

Question 2

What are positional isomers?

Answer 2

The skeleton and functional group could be the same, only with the group attached to a different carbon atom.
These have different physical and often different chemical properties.

Question 3

What are functional group isomers?

Answer 3

Functional group isomers have the same atoms arranged into different functional groups.

Question 4

What are stereoisomers?

Answer 4

Have the same structural formula but a different arrangement in space.
Some alkenes have stereoisomers- because theres a lack of rotation around the C=C double bond.
When the double bonded carbon atoms each have two different atoms or groups attached to them, you get an ‘E-isomer’ and a ‘Z-isomer’.

Question 5

Each of the groups linked to the double bonded carbons is given a priority.
If the two carbon atoms have their ‘higher priority groups’ on opposite sides…

Answer 5

Then its an E isomer.

Question 6

Each of the groups linked to the double bonded carbons is given a priority.
If the two carbon atoms have their ‘higher priority groups’ on the same side…

Answer 6

Then its a Z isomer.

Question 7

What is Cis-trans isomerism?

Answer 7

A special type of E/Z isomerism where the two carbon atoms either side of the double bond have at least one group in common.
The cis-isomer is the one that has two identical groups on the same side of the C=C double bond.
The trans-isomer is the one that has the two identical groups on opposite sides of the C=C double bond.

Question 8

What is meant by the term functional group?

Answer 8

Group of atoms (in a molecule or compound) that is

responsible for the reactions.