Organic Chemistry

Question 1

Hydrocarbons

Answer 1

Compounds containing carbon and hydrogen only

Mainly sourced from crude oil, that is separated into fractions by fractional distillation

Question 2

Homologous series

Answer 2

• Series of compounds with the same functional group
• Differ from their neighbours in the series by CH2
• Can be represented by a general formula
• Have physical properties that vary as the Mr of the compound varies

Question 3

Functional group

Answer 3

• Reactive part of a molecule
• Refers to the atom/group of atoms that gives the compound its characteristic properties
• Defines to which homologous series the compound belongs

Question 4

Structural isomerism

Answer 4

Molecules have the same molecular formula but different structural formula
Chain, position, FG (cyclohexanol vs hexanal)

Question 5

Electrophile

Answer 5

Electron deficient species or a lone pair acceptor eg. H+, NO2+

Question 6

Nucleophile

Answer 6

Electron rich species or a lone pair donor e.g. OH-, :NH3, CN-

Question 7

Heterolytic fission/heterolysis

Answer 7

Unequal splitting of a shared pair of electrons in an asymmetrical covalent bond, producing ions

Question 8

Homolytic fission/homolysis

Answer 8

Equal splitting of a shared pair of electrons in an asymmetrical covalent bond, producing free radicals where each atom receives an electron

Question 9

Alkanes

Answer 9

Homologous series of hydrocarbons with the general formula CnH2n+2
Formed from crude oil by fractional distillation
Because saturated i) alkanes have similar properties ii) generally unreactive

Question 10

Alkenes

Answer 10

Homologous series of hydrocarbons with the general formula CnH2n that contain at least 1 C=C bond
Formed when petroleum is cracked
Important for polymerisation (unsaturated –> saturated)

Question 11

SIGMA bond

Answer 11

End to end overlap of atomic orbitals to form electron sharing e.g. single C-C bond
Strongest type of covalent bond

Question 12

PI bond

Answer 12

Sideway overlap of atomic orbitals above and below the sigma bond and is an area of high electron density between 2C atoms
Bond restricts rotation about the C=C bond, meaning that all atoms lie in the same plane

Alkene: pi and sigma
Alkane: sigma only

Question 13

Halogenoalkane

Answer 13

Homologous series in which one or more of the H atoms in an alkane have been replaced by a halogen
General formula CnH2n+1X

Question 14

Alcohols

Answer 14

Homologous series in which one of the hydrogen atoms in an alkane has been replaced by the -OH functional group
CnH2n+1OH

Question 15

Carboxylic acid

Answer 15

Homologous series with the general formula CnH2n+1COOH

Question 16

Polymerisation

Answer 16

The joining of a large number of monomer (unsaturated) molecules to make a large polymer (saturated) molecule
Alkenes can undergo polymerisation via addition reactions

Question 17

Geometric isomers

Answer 17

Geometric isomers arise in molecules containing

(1) Double bond
(2) Different substituents attached to the C atom either end of the C=C bond

• -> Restricted rotation about the double bond means that the substituent groups on the double bonded carbon atoms can behave differently
• -> In E form substituent groups are held too far apart to interact; in Z form they are closer