Skip to content
    Chemistry A-Level

    Cahn–Ingold–Prelog priority rules

    What Cahn–Ingold–Prelog priority rules means in Chemistry A-Level, as defined for OCR.

    Definitions of Cahn–Ingold–Prelog priority rules

    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 Cahn–Ingold–Prelog priority rules in your own words. Rough notes are fine. This is a self-check, with no mark or grade.

    Reference: OCR

    Rules that rank the two groups on each carbon of the C=C group by comparing the atoms directly attached and giving higher priority to the atom of greater atomic number.
    OCR · Alkenes
    Priority follows these rules: compare atoms directly attached by atomic number, and if tied, work outward along the chain.
    OCR · Alkenes

    Topics that use Cahn–Ingold–Prelog priority rules

    Related terms

    Using Cahn–Ingold–Prelog priority rules 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

    A week of Premium from your first lesson · Then the free plan continues · No card, no charge

    All Chemistry A-Level terms