You don't get a reaction every time two reactants collide.Propose why the particles need to collide with a certain amount of energy.

In a chemical reaction, reactant particles need to collide with a certain amount of energy, known as the activation energy, for the reaction to occur. Here's why:

1. Formation of Activated Complex: When two reactant particles collide, they form an intermediate state known as the activated complex or transition state. This state is highly unstable and requires a certain amount of energy to form.

2. Breaking of Bonds: The formation of the activated complex involves the breaking of bonds in the reactant particles. Bond breaking is an endothermic process, meaning it requires energy. If the colliding particles do not have enough energy, the bonds in the reactants will not break, and no reaction will occur.

3. Formation of New Bonds: After the bonds in the reactants are broken, new bonds form to create the products. Bond formation is an exothermic process, meaning it releases energy. However, the energy barrier for breaking the initial bonds must first be overcome for the reaction to proceed to this stage.

4. Orientation of Particles: The reactant particles also need to collide in the correct orientation for a reaction to occur. Even if the particles collide with enough energy, if they are not oriented correctly, they will not form the activated complex and the reaction will not occur.

In summary, reactant particles need to collide with a certain amount of energy, the activation energy, to overcome the energy barrier of bond breaking and to form the activated complex in the correct orientation. Without this energy, a reaction will not occur every time two reactants collide.