Final answer:
A chemical reaction will occur if the products are more stable than the reactants, as supported by conditions such as proper collision frequency, orientation, and energy.
Step-by-step explanation:
A chemical reaction will occur if the products are more stable than the reactants. It's important to note that a chemical reaction isn't solely dependent on the stability of products or mass differential between reactants and products, due to the law of conservation of mass which states that mass cannot be created or destroyed in a chemical reaction. Therefore, the mass of the products equals the mass of the reactants. For a chemical reaction to occur, several conditions need to be met: reactants must collide frequently, they need to have the proper orientation during collision, and sufficient energy to overcome the energy of activation. Changes such as a shift in color, the production of a gas, the formation of a precipitate, or a transfer of energy are indicators that a chemical reaction has taken place.