If the amount of energy required to break bonds in the reactants is more than the amount of energy released in forming bonds in the products, then the reaction will have a negative change in enthalpy (−ΔH).
exothermic - if more heat energy is released in forming bonds in the products than is taken in when breaking bonds in the reactants. endothermic - if less heat energy is released in forming bonds in the products than is taken in when breaking bonds in the reactants.
