Basic Organic Chemsitry And Isomerism

Question 0

What is a homologous series

Answer 0

A group of organic compounds which have the same general formula eg alkanes

Question 1

What is a functional group

Answer 1

A reactive part of a molecule

Question 2

What are stereo isomers

Answer 2

They have the same structural formula but a different arrangement of atoms in space

Question 3

Describe stereoisomerism

Answer 3

Can twist and rotate a molecule any way around a single bond. But a double bond has a fixed position-you can’t rotate the rest of the molecules around it. Because of the lack of rotation around the double bond, some alkenes have stereoisomers. Stereoisomers happen when each double-bonded carbon atom has 2 different atoms or groups attached to it. Get E or Z isomerism

Question 4

What are the three types of structural isomers

Answer 4

Chain isomers
Positional isomers
Functional group isomers

Question 5

What are chain isomers

Answer 5

Have different arrangements of the carbon skeleton. Some are straight chains and others branched in different ways

Question 6

What are positional isomers

Answer 6

Have the same skeleton and the same atoms or groups of atoms attached. The difference is that the functional group is attached to a different carbon atom

Question 7

What are functional group isomers

Answer 7

Same atoms arranged into different functional groups

Question 8

What does nomenclature mean

Answer 8

Naming organic compounds

Question 9

What is the general formula of the alcohol homologous group

Answer 9

CnH2n+1OH

Question 10

What are optical isomers

Answer 10

Mirror images of each other. Optical isomerism is another type of stereoisomerism. Stereoisomers have the same structural formula but have their atoms arranged differently in space

Question 11

What is a chiral (asymmetric) carbon atom

Answer 11

One that has four different groups attached to it. Possible to arrange the groups in 2 different ways around the carbon atom so that 2 different molecules are made, these molecules are called enantiomers or optical isomers. The enantiomers are mirror images, no matter which way you turn them they can’t be superimposed

Question 12

What is another name for optical isomers

Answer 12

Enantiomers

Question 13

What does it mean if a molecule can be superimposed

Answer 13

They’re achiral and there’s no optical isomerism

Question 14

Optical isomers are optically active. Explain

Answer 14

They rotate plane-polarised light (which only vibrates in one direction). One enantiomers rotates it in a clockwise direction, and the other rotates it in a clockwise direction

Question 15

What is a racemate/ racemic mixture?

Answer 15

It contains equal quantities of each enantiomer of an optically active compound. Racemate don’t show any optical activity, the 2 enantiomers cancel each other’s light rotating effect. Chemists often react 2 achiral things together and get a racemic mixture of a chiral product. This is because when the 2 molecules react there’s an equal chance of forming each of the enantiomers. You can modify a reaction to produce a single enantiomer using chemical methods but it’s difficult and expensive

Question 16

Suggest one advantage and one disadvantage for using a racemic mixture rather than a single enantiomer in medicines

Answer 16

Cheaper as no need to separate enantiomers

May be side effects from one of the enantiomers in the mixture/ only half of the product works

Question 17

How can a pair of stereoisomers be distinguished

Answer 17

Using a polarimeter, plane polarised light will be rotated in opposite directions