GCSE›AQA GCSE Chemistry›Mind mapsBond EnergiesAQA GCSE Chemistry: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsExothermicEnergy transferred to surroundingsTemperature risesCombustion, neutralisationUsed in self-heating cansEndothermicEnergy taken in from surroundingsTemperature fallsThermal decompositionUsed in some cold packsReaction profilesExothermic slopes down overallEndothermic slopes up overallPeak hump is activation energyMinimum energy for colliding particles to reactBond Energiesbreaking and makingkJΔHBonds (HT)Breaking bonds takes energy inForming bonds releases energy outMore released than used → exothermicMore needed than released → endothermicCalculating (HT)Energy change = broken − formedBreak 500 kJ, form 700 kJReleases 200 kJ, so exothermicExam tipsBreaking always takes energy inForming always releases energyJudge type from the surroundings temperature