Chemical reactions occur when molecules or atoms collide in a way 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 true statements regarding energy changes during a reaction. increasing the concentration of reactants increases the number of collisions, and the reaction goes faster. if the heat of reaction, î”đť» , is positive, the energy of the products is lower than the energy of the reactants and the reaction is endothermic. when the activation energy is low, the reaction rate is slow. the activation energy, đť¸a , of the forward reaction is the difference between the energy of the products and the energy of the transition state. decreasing the temperature decreases the kinetic energy of the reactants, and the reaction goes more slowly. reactants must collide with proper orientation and with energy greater than or equal to the activation energy for a reaction to occur. the energy of a collision between atoms or molecules must be greater than or equal to the activation energy, đť¸a , for bonds to be broken.