Organic Mechanisms (AQA A Level Chemistry): Revision Note

You must be able to provide these mechanisms in full if asked for. You must be able to apply your knowledge of what happens in a reaction mechanism to other reactions.

In free-radical mechanisms, half-headed arrows are not required, but using double-headed arrows will be penalised. Radical dots must be shown in free-radical substitution — absence is penalised.

When drawing carbocation intermediates, do not draw a bond to the positive charge — the charge must sit on the carbon atom.

Partial charges must be placed on the correct atoms (e.g., δ⁺ on C and δ^- on X in C-X).

If a C-H bond is broken in a mechanism (e.g., elimination), both the bond and the H atom must be drawn explicitly — "sticks" lose marks here.

Curly arrows must originate from a lone pair or from a bond — arrows starting at an atom score zero.

When showing bond formation, the arrow must go directly to the relevant atom, not to a formal charge.

Drawing extraneous curly arrows (e.g., from a breaking C-Br bond to a spectator K⁺ ion) loses marks.