What must the particles in collision have to initiate a reaction?

To initiate a chemical reaction, the particles involved in the collision must possess a certain minimum energy, known as the activation energy. Activation energy is the threshold energy that must be overcome for the reactants to successfully collide and form products. This requirement arises because, during a collision, particles need enough energy to break bonds in the reactants and rearrange them to form new bonds in the products.

If the energy of the colliding particles is below this threshold, they will simply bounce off one another without resulting in a reaction. Thus, a specific minimum energy level is essential to ensure that the reactants can reach the activated state where the reaction can proceed.

This concept is crucial in understanding reaction kinetics and the factors that influence the rate of a chemical reaction, such as temperature, concentration, and catalysts. Higher temperatures generally increase the average kinetic energy of the particles, leading to a greater number of collisions that exceed the activation energy, thus speeding up the reaction.