Optical isomerism

Question 1

What is optical isomerism?

Answer 1

A form of stereoisomerism, where 2 molecules have the same structural formula but different arrangement of atoms in space.
Optical isomers are non-superimposable mirror images of each other and have a chiral carbon atom.

Question 2

What is a chiral molecule?

Answer 2

A chiral molecule has 4 different groups attached to a carbon atom.

Question 3

What are enantiomers?

Answer 3

We can arrange groups in 2 different ways around a chiral carbon atom. We call these 2 different molecules enantiomers.

These enantiomers are mirror images of each other and are non-superimposable. No matter which way you turn them they will not overlap.

Question 4

What is plane polarised light?

Answer 4

Standard light oscillates in all directions.
When we pass the light through a polaroid filter we produce plane polarised light. This only oscillates in one direction.

Question 5

How can we use plane polarised light to detect optically active compounds?

Answer 5

Optically active isomers will rotate plane polarised light.
One enantiomer rotates light clockwise, the other will rotate it anticlockwise.

Question 6

What is a D enantiomer?

Answer 6

Rotates plane polarised light clockwise

Question 7

What is an L enantiomer?

Answer 7

Rotates plane polarised light anticlockwise

Question 8

When is a carbon asymmetric?

Answer 8

When a C atom is bonded to 4 different groups.