Opotical isomerism ( A-level )

Question 1

what property must a carbon atom have for the molecule to display optical isomerism?

Answer 1

4 different elements/molecules attached to one carbon atom

Question 2

what are the similarities and differences between two optical isomers?

Answer 2

same atoms ans bonds, but they are non-superimposable mirror images of one another. not identical in chemical properties.

differ in the way they rotate plane polarised light- rotate plane of polarisation by the same angle but in different directions

Question 3

what word is used to describe optically active molecules?

Answer 3

chiral

Question 4

what are pairs of isomers called?

Answer 4

Enantiomers

Question 5

what is the chiral centre?

Answer 5

the carbon that has the 4 different elements attached to it

Question 6

how is the chiral centre denoted?

Answer 6

C*

Question 7

how is light polarised?

Answer 7

By passing through a polaroid filter, so oscillations are only in one plane

Question 8

what effect does a racemic mixture have on plane polarised light?

Answer 8

None, as the rotation by each enantiomer cancels out to nothing

Question 9

what effect does the + isomer have on polarised light?

Answer 9

rotates plane of polarisation by x^0 clockwise

Question 10

what effect does the - isomer have on polarised light?

Answer 10

rotates the plane of polarisation by x^0 anti clockwise
( same angle, opposite direction )

Question 11

are racemic mixtures formed in nature? why?

Answer 11

not often, as enzymes mechanisms are 3D so only one enantiomer is formed

Question 12

why is optical isomerism a problem for the drug industry?

Answer 12

sometimes, only one enantiomer is effective due to enyzmes active site being 3D