Chemistry A-Level
propagation
What propagation means in Chemistry A-Level, as defined for AQA, OCR.
Definitions of propagation
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Reference: OCR
A halogen radical reacts with the alkane to form a hydrogen halide and an alkyl radical, then the alkyl radical reacts with a halogen molecule to form the halogenoalkane and a new halogen radical.
A step with one radical in and one radical out, so the radical count is unchanged and the chain continues.
Topics that use propagation
- Reaction mechanisms (AQA A-Level)
- Alkanes (OCR A-Level)
Related terms
- initiation
- termination
- Bond angle of about 109.5°
- Consequences for alkane reactivity
- Curly arrow conventions
- Distinguishing σ-bonds from π-bonds
- Effect of branching on boiling point
- Effect of carbon-chain length on boiling point
Using propagation in the exam
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