Functional group flashcards: what to put on each card for organic chemistry

Why functional group flashcards are worth making

Functional group flashcards are one of the few flashcard decks in organic chemistry that pay off in almost every exam question. A functional group is the part of a molecule that decides how it behaves: an –OH makes an alcohol, a C=O changes the reactivity of everything around it, a –COOH makes a molecule acidic. Once you can spot the groups in a structure, name them and say what they typically do, reaction mechanisms stop being a list of arrows to memorise and start to make sense.

Whether you are doing a chemistry degree, studying pharmacy, or facing the organic part of the chemistry exam in medicine or biology, the core list is much the same. This guide covers which groups to learn, what belongs on each card, a few card types that go beyond 'name this group', and a routine for the weeks before the exam. The chemistry here is standard introductory material; where your course uses different conventions or expects more detail, follow your script.

Which functional groups to learn first

Start with the groups that turn up in nearly every introductory course. It helps to learn them in families, because related groups share behaviour – the carbonyl family in particular is easier to learn together than one group at a time.

You also need one ranking card: the priority order used in IUPAC naming, which tells you which group gives the suffix when a molecule contains several. A common simplified order, from highest to lowest, is: carboxylic acids, anhydrides, esters, acyl halides, amides, nitriles, aldehydes, ketones, alcohols, thiols, amines. Double and triple bonds show up in the name as -ene and -yne, while halogens, nitro groups and ether groups only ever appear as prefixes. Textbooks differ slightly in the details, so copy the order your own course uses.

The groups worth a card each:

• Hydrocarbon groups: alkenes (C=C), alkynes (C≡C) and aromatic rings such as benzene. Alkanes have no functional group, but they make a useful reference card for comparing boiling points and reactivity.
• Single bonds to a heteroatom: haloalkanes (C–F, C–Cl, C–Br, C–I), alcohols (C–OH), ethers (C–O–C), amines (nitrogen bonded to one, two or three carbons) and thiols (C–SH).
• The carbonyl family: aldehydes (C=O at the end of a chain, the carbon also bonded to hydrogen), ketones (C=O between two carbons), carboxylic acids (–COOH), esters (–COO– between two carbon groups), amides (C=O bonded to nitrogen) and acyl chlorides (–COCl).
• Others that appear often: nitriles (–C≡N), nitro groups (–NO2), phenols (–OH directly on an aromatic ring) and acid anhydrides.

What goes on each functional group flashcard

A card that only says 'R–CHO = aldehyde' is a start, but it trains a single kind of recognition. For functional groups flashcards to help in an exam, each group needs four pieces of information. You can put all four on one card with a full answer on the back, or split them into four small cards per group. Smaller cards are easier to test honestly, because you cannot half-know a single fact. Writing the back of each card yourself, from your script, matters more than how neat it looks: if you cannot fill in one of the four fields, that is a gap to close now rather than in the exam. Using the aldehyde as the example:

• Structure description: what the group looks like and what it is bonded to. For an aldehyde: a carbonyl carbon at the end of a chain, bonded to one hydrogen and one carbon (or to two hydrogens in methanal).
• Naming: the suffix when it is the main group, and the prefix when it is not. Aldehyde: suffix -al (ethanal); prefix oxo-, or formyl- for a –CHO substituent.
• Properties: polarity, hydrogen bonding, acidity or basicity, and what that means for boiling point and solubility. Aldehyde: polar C=O but no O–H, so no hydrogen bonds between aldehyde molecules; boiling points lie between those of comparable alkanes and alcohols.
• A typical reaction: one or two that your course expects you to know. Aldehyde: nucleophilic addition at the carbonyl carbon; easily oxidised to a carboxylic acid, which is why aldehydes give a positive Tollens' test and ketones do not.

Example cards for the core organic functional groups

Here are back-of-card summaries for the groups you will meet most often. They are deliberately short; your course may expect more detail on mechanisms or conditions.

• Alkene. Structure: C=C double bond. Naming: suffix -ene (propene). Properties: non-polar, electron-rich double bond. Typical reaction: electrophilic addition, for example HBr adding across the double bond following Markovnikov's rule; alkenes decolourise bromine water.
• Alcohol. Structure: –OH on an sp3 carbon; primary, secondary or tertiary depending on how many carbons are attached to that carbon. Naming: suffix -ol (ethanol), prefix hydroxy-. Properties: hydrogen bonding, so higher boiling points than alkanes of similar size; short-chain alcohols mix with water. Typical reaction: oxidation – primary alcohols to aldehydes and then carboxylic acids, secondary alcohols to ketones; tertiary alcohols resist oxidation under the usual conditions.
• Ketone. Structure: C=O bonded to two carbons. Naming: suffix -one (propanone), prefix oxo-. Properties: polar; accepts hydrogen bonds but cannot donate them. Typical reaction: nucleophilic addition; reduction with sodium borohydride gives a secondary alcohol.
• Carboxylic acid. Structure: –COOH, a carbonyl and a hydroxyl group on the same carbon. Naming: suffix -oic acid (ethanoic acid), prefix carboxy-. Properties: weak acid, strong hydrogen bonding, high boiling points. Typical reaction: with an alcohol and an acid catalyst it forms an ester in a reversible reaction (Fischer esterification); with bases it forms carboxylate salts.
• Ester. Structure: –COO– with carbon groups on both sides. Naming: alkyl alkanoate (ethyl ethanoate). Properties: polar, no O–H, many have fruity smells. Typical reaction: hydrolysis back to carboxylic acid and alcohol; in base this is called saponification and gives the carboxylate salt.
• Amine. Structure: nitrogen with a lone pair, bonded to one, two or three carbons. Naming: suffix -amine (ethanamine), prefix amino-. Properties: basic and nucleophilic because of the lone pair; primary and secondary amines can donate hydrogen bonds. Typical reaction: protonation by acids to give ammonium salts; reaction with acyl chlorides to give amides.
• Amide. Structure: C=O bonded to nitrogen. Naming: suffix -amide (ethanamide). Properties: the nitrogen lone pair is delocalised into the carbonyl, so amides are barely basic; high boiling points. Typical reaction: hydrolysis to a carboxylic acid and an amine or ammonia, which needs harsher conditions than ester hydrolysis.
• Haloalkane. Structure: halogen bonded to an sp3 carbon. Naming: prefix only – fluoro-, chloro-, bromo-, iodo- (2-bromopropane). Properties: polar C–X bond with an electrophilic carbon. Typical reaction: nucleophilic substitution (SN1 or SN2) competing with elimination (E1 or E2).
• Nitrile. Structure: –C≡N. Naming: suffix -nitrile (ethanenitrile), prefix cyano-. Properties: strongly polar. Typical reaction: hydrolysis to a carboxylic acid; reduction, for example with lithium aluminium hydride, to a primary amine.

Card types beyond 'name this group'

Once the basics sit, recognising a group on its own gets too easy – and exams show you whole molecules, not isolated groups. In organic functional groups flashcards, mixed card types like the ones below tend to reveal your real weak spots quickly. If you keep confusing esters and ethers, for example, make a pair card for exactly that and test it more often than the rest.

• Spot the groups: a real molecule on the front, all of its functional groups on the back. Aspirin, for instance, contains a carboxylic acid, an ester and an aromatic ring; paracetamol contains a phenol, an amide and an aromatic ring.
• Tell them apart: pairs that look alike. Aldehyde or ketone? Ester or ether? Amine or amide? Alcohol or phenol? The back explains the structural difference and one test or property that separates them.
• Name it: a short structure on the front, the IUPAC name on the back, using the priority order to choose the suffix.
• What happens next: a starting group and reagent on the front (a primary alcohol heated under reflux with acidified potassium dichromate), the product on the back (a carboxylic acid).
• Draw it: a name on the front; you sketch the structure on paper before you turn the card. Drawing catches mistakes that reading a card never will.

A practice routine before the organic chemistry exam

Functional groups are best learned early and kept fresh, because later topics such as mechanisms, synthesis routes and spectroscopy all depend on them. Treat the routine below as a guide, not a rule: the point is to come back to the same cards several times with gaps in between, and to let your mistakes decide what you review next.

If your functional group table lives in your lecture slides or on a handwritten sheet, you can photograph it or add the slides to NotizAI and get a note with flashcards and a quiz from that material as a starting set. Chemistry is unforgiving about details, so check the generated cards against your script – where they differ, the script wins – and build your own pair and reaction cards on top.

A four-week plan for ochem functional groups flashcards before the Klausur could look like this:

• Four weeks before: make or complete the deck from your script and lecture slides. Go through it once a day in short sessions, saying each answer out loud before you turn the card.
• Three weeks before: sort the cards into three piles – known, shaky, wrong – and spend most of each session on the shaky and wrong piles. Add spot-the-groups and tell-them-apart cards.
• Two weeks before: mix the functional group cards with reaction cards and questions from past exam papers. Draw structures from names on paper.
• Final week: a short daily round through the whole deck, plus timed practice on old exams. Any card you still miss goes onto one page that you read on the morning of the exam.