What does collision theory state is necessary for a chemical reaction to occur?

Collision theory is a fundamental principle in chemical kinetics that explains how and why chemical reactions occur. According to this theory, for a chemical reaction to take place, reactant particles must collide with sufficient energy and in the correct orientation.

Sufficient energy, often referred to as activation energy, is necessary to break the existing bonds in the reactants so that new bonds can form in the products. Additionally, the proper orientation during a collision means that the reacting particles are aligned in a way that allows for effective overlap of their electron clouds, leading to bond formation.

While it is true that different states of matter can affect the nature of the collisions (like gaseous states or solids), it is not a requirement for all reactant particles to be in a specific state for a reaction to occur, making other options less relevant. Similarly, the presence of a catalyst can enhance the rate of a reaction but is not required for a reaction to take place. Hence, the necessity for collision with energy and orientation remains a key principle in understanding how chemical reactions occur.