Breaking and making bonds: using bond energies
I can describe how bond making and breaking use or release energy, and use bond energies to calculate whether a reaction is exothermic or endothermic.
Breaking and making bonds: using bond energies
I can describe how bond making and breaking use or release energy, and use bond energies to calculate whether a reaction is exothermic or endothermic.
Lesson details
Key learning points
- The energy needed to break bonds and the energy released when bonds are formed can be calculated from bond energies.
- The difference between the energy needed to break bonds and the energy released is the overall energy change.
Common misconception
Pupils often make mistakes when identifying the different types of bonds and the number of each in a molecule. They may also reverse the calculation of the overall energy change, as make - break.
Molecules can be complex and should be drawn to show all the bonds. Emphasis that double and triple covalent bonds are different to single bonds. Pupils should be instructed to consider whether a reaction is exothermic or endothermic.
Keywords
Endothermic - An endothermic chemical reaction is a type of reaction in which energy is transferred from the surroundings to the products, e.g. photosynthesis.
Exothermic - An exothermic chemical reaction is a type of reaction in which energy is transferred from the reactants to the surroundings, e.g. combustion.
Activation energy - The minimum energy that the particles must have in order to react is known as the activation energy.
Bond energy - The energy required to break a covalent bond, or released when making a covalent bond. is known as the bond energy.
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
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