Year 10 - Science
Breaking and making bonds
Energy changes in reactions
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit covers bulk material properties related to bonding and intermolecular forces and explores bond breaking, bond making, activation energy, and reaction profiles. It focuses on selecting appropriate techniques, translating data, and presenting observations using various models.
Lesson Summary
You will learn to describe how bond making and breaking use or release energy.
Key Notes
- In all chemical reactions, bonds in the reactants need to be broken before the reaction can happen
- Energy must be supplied to break bonds in the reactants
- Energy is released when bonds in the products are formed
- The difference between the energy needed to break bonds and the energy released is the overall energy change
Vocabulary To Learn
- 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.
Common Mistakes To Avoid
- Pupils often confuse the ideas that bonds require energy to break i.e. endothermic process and that energy is released forming bonds i.e. exothermic process.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
In all chemical reactions, bonds in the reactants need to be broken before the reaction can happen. Energy must be supplied to break bonds in the reactants.
2. Define this scientific word and use it in context. 'endothermic'
An endothermic chemical reaction is a type of reaction in which energy is transferred from the surroundings to the products, e.g. photosynthesis. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Pupils often confuse the ideas that bonds require energy to break i.e. endothermic process and that energy is released forming bonds i.e. exothermic process. Correction: Bonds will not break unless energy is absorbed to do so. The formation of a bond releases energy to the surroundings.
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