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What is the structure of benzene
Each carbon atom is sp hybridised and forms 3 sigma bonds
The unhybridised p orbitals overlap in both directions, forming a delocalised pi electron cloud.
This means the electron density is concentrated in donut shaped rings above and below the plane of the ring.
How are esters named
The alcohol group name is at the start, followed by the carboxylic acid group name.
eg. methanoic acid + ethanol → ethyl methanoate
What is the Sn2 mechanism and how does it occur
Sn2 occurs in primary halogenoalkanes, where at least 2 H atoms are attached to the C of the C-H bond
The carbon is open to attack by the nucleophile due to the small size of the H atoms
An unstable transition state is formed where the C is weakly bonded to both the halogen and the nucleophile
The C-halogen bond breaks heterolytically and the halogen is released.
How does the arrangement of the atoms change in the Sn2 mechanism
The nucleophile attacks the C on the opposite side from the leaving group, causing an inversion in the arrangement.
When does Cis-trans and E-Z isomerism occur
In a double bond, as there is no free rotation
And in cycloalkanes
What are cis-trans isomers
Where the molecule contains 2+ different groups attached to the double bond/ring
Cis isomers are where the groups are on the same side of the double bond/ring
Trans isomers have the group on opposite sides.
When is E-Z isomerism used
When all the groups are different attached to the double bond, so no same groups can be distinguished.
How do the rules of priority determine the E-Z structure
If the groups are singular atoms, the highest atomic number has priority
Longer hydrocarbon chains have higher priority
If the 2 highest priority groups are on the same side it is a Z isomer
If the 2 highest priority groups are on opposite sides it is a E isomer
What are stereoisomers
A chiral carbon (C attached to 4 different groups) is the stereocentre of a stereoisomer.
They have 2 different enantiomers which are mirror images of each other
What is a racemic mixture
Where a mixture contains equal amounts of 2 enantiomers.
How can we distinguish between 2 enantiomers
They rotate in plane polarised light in opposite directions.
What kind of reaction do alkanes take part in
free radical substitution (halogenation)
What is the initial stage of halogenation
Initiation stage
The halogen is broken from a diatomic molecule to 2 monatomic atoms by UV light
What occurs in the propagation stage of halogenation
The halogen free radical react with the alkane, making alkyl free radicals and hydrogen (halogen)
The second free radical can react with another alkane
What occurs in the termination stage of halogenation
2 free radicals collide to end the chain reaction.
Which reactants perform electrophilic addition
Alkene + halogen
Alkene + hydrogen halide
Alkene + steam (with catalyst)
Alkene + hydrogen (with nickel catalyst and 150 degrees)
What is the first step of electrophilic addition
The electrophile attacks the pair of electrons in the double bond . This forms a positive carbocation intermediate and breaks the bond in the electrophile heterolytically.
What is the second step of electrophilic addition
The negative ion remaining from the heterolytic fission of the electrophile the attacks the carbon atom holding the positive charge on the intermediate.
what conditions are needed to dehydrate a alcohol
Heating at 170 degrees
With concentrated phosphoric acid, sulfuric acid or hot aluminium oxide
What are primary alcohols oxidised to
aldehydes
And they can be further oxidised into carboxylic acids
What are secondary alcohols oxidised to
ketones, occurs under reflux
What are tertiary alcohols oxidised to
they do not oxidise
Why do halogenoalkanes undergo substitution
Because there is a dipole as the C-Halogen bond has an electronegativity difference.
What does the strength of a carboxylic acid depend on
The ease with which the O-H bond is broken
This is affected by groups on the carbon chain which reduce the strength of the O-H bond, this makes it more acidic
How are carboxylic acids reduced
They are reduced to aldehydes, by using strong reducing agents such as lithium aluminium hydride.
Note 
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