Addition

The double bond dissolves back to single bond and new bonds reach out to A and B whose bond is also dissolving.

A_E – electrophylic addition – электрофильное присоединение

A_N – nucleophylic addition – нуклеофильное присоединение

Elimination (E)

This is the opposite of addition i.e. a double bond is created when two groups on adjacent carbons are rejected by the molecule. The groups are just those groups which were added in the first place. The only one we cannot do is the elimination of H-H bond.

Substitution (S)

One non-carbon group is replaced by another group. Usually only occurs at a singly bonded site. The only example so far is halogen/UV on alkanes but alkanols and haloalkanes love a bit of substitution as well.

S_E – electrophylic substitution – электрофильное замещение

S_N – nucleophylic substitution – нуклеофильное замещение

Condensation and Hydrolysis

Condensation is where two molecules join together and lose a simple molecule. e.g. water or carbon dioxide. Hydrolysis is the reverse.

Oxidation and Reduction

Are opposite of each other. Oxidation is either adding O or making it have a double bond or removing H or both. Reduction is the opposite.

Isomerization

This is when a substance changes into another form with different properties but the same molecular formula. For example:

catalyst

n -pentane → iso -pentane

The different forms are called “isomers”, and the phenomenon of the existence of different forms “isomerism”.