Topic 6A: Introduction to organic chemistry

Question 1

what is a hydrocarbon

Answer 1

a compound containing only carbon and hydrogen atoms

Question 2

what is the empirical formula

Answer 2

the simplest whole number ratio of atoms of each element in a compound

Question 3

what is the molecular formula

Answer 3

the true number of atoms of each element in a compound

Question 4

what is the general formula

Answer 4

All members of a homologous organic series follow the general formula. For example, alkanes have the general formula CnH2n+2

Question 5

what is the structural formula

Answer 5

shows the structural arrangement of atoms within a molecule
butane - CH3 CH2 CH2 CH3

Question 6

what is the displayed formula

Answer 6

shows the structural arrangement of atoms within a molecule

Question 7

what is the skeletal formula

Answer 7

shows the bonds in a compound between the carbon atoms only

Question 8

what are all the prefixes for carbon atoms from 1 - 10

Answer 8

1 - meth-
2 - eth-
3 - prop-
4 - but-
5 - pent-
6 - hex-
7 - hept-
8 - oct-
9 - non-
10 - dec-

Question 9

define homologous series

Answer 9

a group of compounds which have the same functional group and general formula

Question 10

what are three features of a homolgous series

Answer 10

• all have the same functional group
• all have the same general formula
• each compound in the series differs by a CH2 unit

Question 11

define functional group

Answer 11

a group of atoms responsible for the characteristic reactions of a particular compound

Question 12

what are the different homologous series
(10)

Answer 12

SERIES SUFFIX/PREFIX EXAMPLE
Alkanes -ane Propane (CH3CH2CH3)
Branched alkanes Alkyl- Methylpropane (CH3C(CH3)CH3)
Alkenes -ene Propene (CH3CH=CH2)
Halogenoalkanes Fluoro- / Chloro- / Bromo- / Iodo- Chloroethane (CH3CH2Cl)
Alcohols -ol Ethanol (CH3CH2OH)
Aldehydes -al Ethanal (CH3CHO)
Ketones -one Propanone (CH3COCH3)
Carboxylic acids -oic acid Ethanoic acid (CH3COOH)
Esters Alkyl- oate Ethyl ethanoate (CH3COOCH2CH3)
Amides -amide Ethanamide (CH3CONH2)

Question 13

what are the different reactions
(7)

Answer 13

-addition
-elimination
-substitution
-oxidation
-reduction
-hydrolysis
-polymerisation

Question 14

what is an addition reaction

Answer 14

joining two or more molecules together to form a larger molecule

Question 15

what is an elimination reaction

Answer 15

when a small group of atoms breaks away from a larger molecule to form a c=c bond

Question 16

what is a substitution reaction

Answer 16

when one species is replaced by another

Question 17

what is a oxidisation reaction

Answer 17

a species gains oxygen and loses at least on electron

Question 18

what is a reduction reaction

Answer 18

a species looses oxygen and gains of electrons

Question 19

what is a hydrolysis reaction

Answer 19

breaking the bonds of a molecule by a reaction with water

Question 20

what is a polymerisation reaction

Answer 20

joining together lots of small/simple monomers to form giant molecules (polymer)

Question 21

what is an isomer

Answer 21

molecules with the same molecular formula but different arrangement of atoms within the molecule

Question 22

what are the two types of isomers

Answer 22

• structural isomers
• stereoisomers

Question 23

what are the three types of structural isomers

Answer 23

• chain isomers
• positional isomers
• functional group isomers

Question 24

how are chain isomer different

Answer 24

• differ in the carbon skeleton arrangement ( eg straight chain vs branched chain)

Question 25

positional isomers

Answer 25

• the functional group is attached at different carbon atoms

Question 26

functional group isomers

Answer 26

• the atoms form different functional groups

Question 27

what is stereoisomerism

Answer 27

molecules which are connected in the same way but have different spatial arrangements of atoms

Question 28

what are the two types of stereoisomerism

Answer 28

• e/z isomerism
• cis trans isomerism

Question 29

what is the difference between e isomer and z isomer

Answer 29

• e isomer means the functional groups are on opposite sides
• z isomerism is when the functional group is on the same sideH Cl H H
  l l l l
  C = C C = C
  l l l l
  Cl H Cl Cl
  E Z

Br Cl
l l
C = C
l l
F H
Z isomerism - as Br and Cl have a higher atomic number that F and H, so they have a higher priority
the atoms with a higher priority are on the same side so this is a z isomer

Question 30

what is the difference between cis / trans isomerism and E/Z isomerims

Answer 30

• cis and trans can only be used when there are hydrogen atoms to compare the other two groups