Organic mechanism

What is organic mechanism?

An organic mechanism shows the step-by-step movement of electron pairs during a reaction, drawn with curly arrows. Each arrow starts from a lone pair, double bond, or single bond and ends at the atom or bond receiving the electrons. Major mechanism types at A-Level: free-radical substitution (alkane + halogen + UV), electrophilic addition (alkenes), nucleophilic substitution (halogenoalkanes), elimination, electrophilic substitution (benzene), nucleophilic addition. Examiners reject arrows drawn the wrong way around.