# Explain why breaking bonds requires energy and forming bonds releases energy, and use this idea to explain how you can determine whether an overall chemical reaction is exothermic or endothermic.

> AQA A-Level Chemistry (7405) — 3.1.4 Energetics · Explain · 5 marks

## Mark scheme (5 marks)

1. Breaking bonds requires energy (energy is taken in / absorbed)
2. Forming bonds releases energy (energy is given out)
3. If energy required to break bonds is greater than energy released forming bonds, the reaction is endothermic (overall energy is absorbed from the surroundings)
4. If energy released forming bonds is greater than energy required to break bonds, the reaction is exothermic (overall energy is released to the surroundings)
5. The difference between the energy needed to break bonds and the energy released forming bonds gives the overall energy change of the reaction

## Key terms

- [exothermic](https://www.gradenine.co.uk/glossary/exothermic)
- [endothermic](https://www.gradenine.co.uk/glossary/endothermic)

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-breaking-bonds-requires-energy-4b8ef981) · Published by Druglandscape Ltd.