Energetics
4.13 understand the use of ΔH to represent molar enthalpy change for exothermic and
endothermic reactions
4.14 represent exothermic and endothermic reactions on a simple energy level diagram
4.15 recall that the breaking of bonds is endothermic and that the making of bonds is
exothermic
Just remember this! To break smth, obviously you need energy, so you need to take it in, hence breaking of bonds is endothermic. When substances form bonds, it's usually to become more stable, and thus they release energy. E.g. reactive elements like sodium react with chlorine to form sodium chloride, your common table salt, and this is a very stable ionic compound, and the reaction is exothermic. (less energy, less violently reactive...makes sense right?)
endothermic reactions
4.14 represent exothermic and endothermic reactions on a simple energy level diagram
4.15 recall that the breaking of bonds is endothermic and that the making of bonds is
exothermic
Just remember this! To break smth, obviously you need energy, so you need to take it in, hence breaking of bonds is endothermic. When substances form bonds, it's usually to become more stable, and thus they release energy. E.g. reactive elements like sodium react with chlorine to form sodium chloride, your common table salt, and this is a very stable ionic compound, and the reaction is exothermic. (less energy, less violently reactive...makes sense right?)