Cambridge IGCSE Chemistry 0620 Topic 11 Organic Chemistry

11.1 Formulae, Functional Groups & Terminology
11.2 Naming Organic Compounds

Interactive MSH lesson with embedded videos, student biodata, and 30 marks of short-answer questions submitted for manual marking.

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Assessment mode

Manual marking required. Students submit short-answer responses only. No answer key is stored in the front end.

Student biodata

Embedded video lessons

11.1 Formulae, functional groups and terminology

11.2 Naming organic compounds

Core lesson notes

Displayed formula

Shows every atom and every bond in a molecule.

Ethane: H H | | H-C-C-H | | H H

Structural formula

An unambiguous description of how atoms are arranged, for example CH3CH2OH.

Functional group

The atom or group of atoms that determines the chemical properties of a homologous series.

Homologous series

A family of similar compounds with the same functional group and similar chemical properties.

General formulae

Homologous seriesKey feature / functional groupGeneral formulaExample
AlkanesCarbon-carbon single bonds onlyCnH2n+2Ethane: C2H6
AlkenesC=C double bondCnH2nEthene: C2H4
Alcohols–OHCnH2n+1OHEthanol: C2H5OH
Carboxylic acids–COOHCnH2n+1COOHEthanoic acid: CH3COOH

Supplement notes

Structural isomers

Structural isomers have the same molecular formula but different structural formulae.

C4H10: CH3CH2CH2CH3 and CH3CH(CH3)CH3

Characteristics of a homologous series

  • Same functional group
  • Same general formula
  • Successive members differ by –CH2–
  • Trend in physical properties
  • Similar chemical properties

Short-answer assessment: 30 marks

Answer all questions in complete sentences where appropriate. These responses will be submitted to the backend for manual marking.

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Q1. Define the term displayed formula.

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Q2. Define the term functional group.

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Q3. State the general formulae for alkanes, alkenes, and alcohols.

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Q4. Explain why alkanes are described as saturated hydrocarbons.

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Q5. Explain why ethene is described as unsaturated.

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Q6. Describe three characteristics of a homologous series.

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Q7. Name and give the molecular formula of the alkane with three carbon atoms.

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Q8. Name CH3CH2OH and identify its homologous series.

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Q9. Name CH3COOH and identify the functional group present.

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Q10. Explain what structural isomers are, using C4H10 as an example.

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Q11. Name and draw or describe the structural formulae of but-1-ene and but-2-ene.

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Q12. A compound has the formula C4H9OH. Identify the homologous series, name one possible compound, and explain how the formula fits the general formula.

Submit for manual marking

Total marks: 30   |   Status sent to backend: Manual marking required