isomerism

Question 1

what is an isomer and an example

Answer 1

molecules with the same formula but different structure

glucose and fructose

Question 2

what is a stereoisomer and geometric stereoisomer

Answer 2

molecules with the same structure but different configuration (bond rotation)

geometric stereoisomers have double carbon bonds so bond rotation is not possible, use cis/trans configuration

Question 3

what is cis and trans configuration

Answer 3

cis: groups around a double bond are both on top or bottom. low mp and has kinks
trans: groups are diagonal. high mp

if one if the carbon has 2 identical groups, cis/trans not possible

Question 4

what does optically active mean

Answer 4

molecule rotates plane of polarised light, has chiral carbon

Question 5

what does a polarimeter do

Answer 5

measures direction and rotation of polarised light

Question 6

what is r,s designation

Answer 6

enantiomer is given notation using cip priority

r is right
s is left

Question 7

what is +,- designation

Answer 7

rotation of plane polarised light of enantiomer

+ is right
- is left

Question 8

what is D,L designation

Answer 8

which side the OH group is on on an enantiomer

d is right
l is left

Question 9

what is an enantiomer and examples

Answer 9

non superimposable mirror image molecule - each has different biological properties

taste receptors bind to flavour molecules
enzymes bind to substrates
drug molecules - different effects

Question 10

what is a racemic mixture

Answer 10

mix of enantiomers

used in pharmaceuticals