| Class | Functional Group | Structure | Suffix / Prefix |
|---|---|---|---|
| Alkane | Alkyl (C–C) | – | –ane |
| Alkene | Alkenyl (C=C) | >C=C< | –ene |
| Alcohol | Hydroxyl | –OH | –ol |
| Aldehyde | Carbonyl (terminal) | –CHO | –al |
| Ketone | Carbonyl (internal) | >C=O | –one |
| Carboxylic acid | Carboxyl | –COOH | –oic acid |
| Ester | Ester | –COO– | –oate |
| Amine | Amino | –NH₂ | –amine |
| Amide | Amido | –CONH₂ | –amide |
| Halogenoalkane | Halogeno | –X (F, Cl, Br, I) | fluoro- / chloro- etc. |
| Ether | Alkoxy | –O– | alkoxy- (prefix only) |
⚠️ Examiner Trap. "Class" vs "Homologous Series"
All molecules with the same functional group belong to the same class. A homologous series is stricter. Members must have the same general formula and differ by –CH₂– units. These terms are NOT interchangeable.
⚠️ "Class" vs "Functional Group Name"
The IB tests the distinction: the class is "alcohol" but the functional group name is "hydroxyl". The class is "carboxylic acid" but the functional group is "carboxyl". Don't mix these up!
⚠️ Amine vs Amide Confusion
Amines contain –NH₂ (amino group). Amides contain –CONH₂ (a carbonyl bonded to nitrogen, amido group). These are completely different functional groups with different properties. Don't confuse them.
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