Change the group. Change the molecule.
Addition converts a C=C bond into single bonds while adding atoms across it. Alkenes react with H₂ over a metal catalyst, with halogens, or with water under acid catalysis. For simple unsymmetrical additions under the usual conditions, Markovnikov’s rule predicts H joining the carbon already carrying more H atoms.
Substitution replaces an atom or group: a haloalkane with aqueous hydroxide can form an alcohol, while excess ammonia can form an amine. Alkane halogenation needs UV light. Alcohols can react with hydrogen halides to form haloalkanes.
Elimination removes a small molecule to form a double bond. Heating a suitable haloalkane with ethanolic hydroxide favours elimination. Reagents alone are not enough: aqueous versus ethanolic conditions can change the pathway.
Spot the functional group
Condensed structural diagrams. Bonds show connectivity, not measured bond angles. Compare the molecular formula with the arrangement of atoms.
Assumed knowledge
Track carbon atoms and check valence; detailed substitution mechanisms are not required.
Learning checkpoints & source
YOUR SYLLABUS CHECKPOINT- Identify organic reaction classes and products.
- Apply Markovnikov’s rule.
- Specify reagents and conditions.