Chemical reactions occur when molecules or atoms collide so that the bonds between atoms break and new bonds form. breaking the bonds of the reactants requires energy; whereas, bond formation releases energy. select the statements regarding energy changes during a reaction that are true.

If two substances react and the temperature of the mixture decreases, the reaction is endothermic. If two substances react and the temperature of the mixture increases, the reaction is exothermic. A chemical reaction involves the breaking of bonds in the reactants and the forming of bonds in the products.