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In this lesson students will learn what a bond energy is and how to use bond energies to calculate the overall energy change of a chemical reaction. 

This lesson also links the overall energy calculations to the reaction profile diagrams students will have met in “Energy Changes 1”, allowing students to make visual links between their calculations and the profile diagram of the reaction taking place. 

This lesson is the first lesson in the “Energy Changes 2” topic, and assumes that students have already learned about reaction profile diagrams and the basics of exothermic and endothermic reactions. 

Lesson Objectives:

• Describe what a bond energy is
• Know whether breaking and making bonds are exothermic or endothermic
• Calculate the overall energy changes for reactions using given bond energy values

Resource features:

• Interactive powerpoint including teacher delivery notes and full answers throughout
• Plenary task
• Stretch and challenge tasks throughout
• Clear diagrams, worked examples and scaffolding for calculations

Resource includes:

• Lesson Powerpoint (pptx.)
• Overall Energy Change Calculations: Student Worksheet (PDF)
• Overall Energy Change Calculations: Answer Sheet (PDF)
• Printable Bond Energy Values Tables for students (PDF)