What must happen before a chemical reaction can begin?

Before a chemical reaction happens, what should happen is:

reagent contact, chemical affinity, favorable collisions, and activation energy.

Explanation:

Contact between reagents: In order for the reactant molecules to collide with each other, they must come into contact. For example, sodium is a metal element that reacts with oxygen, oxidizing in minutes when in contact with air. chemical Affinity: This property refers to the ability of one substance to react with another, because even if two or more substances are brought into contact but there is no affinity between them, the reaction will not occurfavorable collisions: For a chemical reaction to occur, the molecules of the reagents that came in contact must effectively collide. The greater the number of favorable collisions, the faster the chemical reaction will be. Activation Energy: For collisions to be favorable and result in a chemical reaction, the reagents must have a minimum energy, which is the activation energy.  Activation energy is required for the formation of the activated complex, that is, an intermediate structure between reactants and products, where reactant bonds are being weakened and product bonds are being formed.