Chemistry A-Level
isotopes
What isotopes means in Chemistry A-Level, as defined for AQA, OCR.
Definitions of isotopes
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 isotopes in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: AQA
Atoms with the same number of protons but different numbers of neutrons, because the number of neutrons in a nucleus can vary while the proton count stays fixed.
Atoms of the same element with different numbers of neutrons and different masses.
Topics that use isotopes
- Mass number and isotopes (AQA A-Level)
- Atomic structure and isotopes (OCR A-Level)
Related terms
- atomic number
- mass number
- relative isotopic mass
- abundance ratios
- acceleration to constant kinetic energy
- base peak
- Calculation accuracy
- carbon-13 satellite
Using isotopes 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.
Start free
All Chemistry A-Level termsA week of Premium from your first lesson · Then the free plan continues · No card, no charge