I am studying the activation energy of a reaction, and I notice that it says when the products are more stable than the reactants the reaction is exothermic, and endothermic when the products are less stable than the reactants. It doesn't say why, but my supposition is that when the products are less stable than the reactants, they need to absorb heat from the environment to get enough energy for the reaction to happen. As for when the products are more stable than the reactants, there is an excess of energy, so it releases that energy as heat. I just want to know if this is correct. Also, they show a potential energy vs. reaction progress graph for an exothermic and endothermic reaction, and the exothermic graph has the products with less potential energy than the products, and the endothermic graph has the products with more potential energy than the reactants. Does having higher stability mean less potential energy?