Homologous series
What Homologous series means in Chemistry A-Level, as defined for AQA, OCR.
Definitions of Homologous series
Exam boards and our study guides word this term in slightly different ways. Learn the version your board uses.
Check what you remember
Read the wording for your board, then hide it and explain Homologous series in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: OCR
A family of organic compounds with the same functional group, the same general formula and similar chemical properties, where successive members differ by a CH₂ unit.
A series whose members are all represented by the same general formula, which is why it is written algebraically rather than as a single molecular formula.
A series of organic compounds having the same functional group but with each successive member differing by CH₂.
A family of compounds that share one functional group, so its members share chemical properties.
Members share a general formula and functional group but differ by CH₂ units.
A family of organic compounds with the same functional group, same general formula, and similar chemical properties.
Topics that use Homologous series
- Elimination (AQA A-Level)
- Nomenclature (AQA A-Level)
- Basic concepts of organic chemistry (OCR A-Level)
Related terms
- Displayed formula
- Functional group
- General formula
- Molecular formula
- Alphabetical ordering of substituents
- alphabetical prefixes
- Aromatic compound
- carbocation intermediate
Using Homologous series in the exam
Check the command word and mark scheme for your exact question. After comparing your explanation with the reference, use the term in an answer on the linked topic. This practice does not predict an exam mark.
Practise Chemistry questions
Create a free account to answer exam-style questions on this topic and get feedback on your answers.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge