Collision Theory states in order for a reaction to occur, these items must happen:

1. A collision must occur between the particle (they need to touch) 

2. The collision must occur with sufficient energy - this minimum amount of energy is referred to as activation energy

3. The collision must occur in the correct orientation. 

💡🧠 Helpful way to remember:  C - E - O    Collision, sufficient Energy, and Orientation 

Watch TedEx - How to Speed up Chemical Reactions (and get a date)