Isomerism Flashcards Preview

Advanced Higher Chemistry: Unit 2 - Organic Chemistry > Isomerism > Flashcards

Flashcards in Isomerism Deck (25)
Loading flashcards...
1
Q

What are the two types of isomerism?

A

strucutral isomerism

stereoisomerism

2
Q

What can stereoisomerism be split into?

A

geometric isomerism

optical isomerism

3
Q

What is meant by structural isomers?

A

Molecules with the same molecular formula but different structural formula

4
Q

What are stereoisomers?

A

molecules with the same molecular formula with a different spatial arrangement of their atoms. Thet are non-superimposable.

5
Q

When does geometric isomerism occur?

A

in molecules where there is no free rotation about the carbon to carbon bond

6
Q

What does ‘cis’ mean?

A

on the same side of the fixed bond

7
Q

What does ‘trans’ mean?

A

on the opposite side of the fixed bond

8
Q

What do geometric isomers sometimes differ in?

A

their physical and chemical properties

9
Q

Why do some geometric isomers differ in their physical and chemical properties?

A

due to differences in their ability to pack together

10
Q

What are optical isomers?

A

non-superimposable mirror images of each other

11
Q

What are molecules which have no symmetry said to be?

A

chrial

12
Q

If asked to draw an optical isomer, what must you always draw along withit?

A

the original isomer

13
Q

What are optical isomers also known as?

A

enantiomers

14
Q

What is a racemic mixture?

A

a mixture of equal quantities of enantiomers

15
Q

What does light passing through a polarisiting filter vibrate in?

A

one plane only

16
Q

What hapeens when polarized light passes through a solution containing an optical isomer?

A

the polarized light is rotated

17
Q

What can the direction of rotation be?

A

right or left

18
Q

What name is given if the direction of rotation is right?

A

dextrotatory

19
Q

What name is given if the direction of rotation is left?

A

laeveorotatory

20
Q

In terms of plane polarised light (ppl), what will enantiomers do?

A

rotate pple by equal and opposite amounts

21
Q

What effect does a reacemic mixture have on ppl?

A

it is optically in active and has no effect on ppl

22
Q

What is the angle of rotation denoted by and what is it measured in?

A

theta and in degrees

23
Q

State 3 properties of optical isomers.

A
  • same physical properties i.e. melting/boiling point
  • are often present in equal proportions (racemic mixtures)
  • same chemical properties, except when in a chiral environment i.e. when other chiral molecules are present
24
Q

How many optical isomers are normally present in living things?

A

1

25
Q

What are many medicines and why is this the case?

A

racemic mixtures because it is too costly to separate the isomers
e.g. Salbutamol - one form is more pharmacologically active
Thalidomide - one enantiomer damaged the unborn baby