Specification Point 3.6C (Paper 2C Only):
Know that bond-breaking is an Endothermic process and that bond-making is an Exothermic process

Endothermic and Exothermic Reactions

Whether a reaction is endothermic or exothermic depends on the difference between the energy needed to break bonds and the energy released when new bonds form.


  • If more energy is absorbed than it releases, this reaction is endothermic
  • More energy is required to break the bonds than make the bonds
Endothermic, Edexcel IGCSE Chemistry


  • If more energy is released than is absorbed, this reaction is exothermic
  • More energy is released making new bonds than energy required to break the bonds

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.