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Chemistry · Grades 10–12

Recognize common functional groups

Locate the actual group rather than classifying by one atom alone.

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Learn the idea

Alcohol

A simple alcohol has an O–H group attached to a saturated carbon; phenols are a related but distinct class.

Carbonyl

A carbonyl is C=O; its neighbors distinguish aldehydes, ketones, acids, esters and amides.

Amines

An amine has nitrogen bonded to carbon and/or hydrogen without the amide carbonyl attachment.

Whole structure

A molecule may contain more than one functional group.

Worked examples

Which group identifies a carboxylic acid in a simple structure?

The carboxyl group contains a carbonyl and hydroxyl on the same carbon.

–C(=O)OH.

CH₃CH₂OH is classified as what in these examples?

Its hydroxyl is bonded to a saturated carbon.

An alcohol.

Check your understanding

  1. What group do aldehydes and ketones share?

    1. A triple C≡C bond.
    2. An O–O bond.
    3. A carbonyl C=O.

  2. Which condensed pattern represents an ester?

    1. R–C(=O)–O–R′.
    2. R–NH₂ only.
    3. R–O–R′ only.

  3. Why cannot every oxygen-containing organic molecule be called an alcohol?

Answers and marking notes

Answers and marking notes
  1. A carbonyl C=O.

    Both contain the carbonyl group but differ in attached groups.

  2. R–C(=O)–O–R′.

    An ester has a carbonyl carbon attached to an oxygen bonded to another carbon group.

  3. Oxygen occurs in many groups, including ethers, carbonyls and esters.

    Classification depends on connectivity, not just element presence.

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.