1. Section 17.1 Part II-Collision Theory We’ve talked about reaction rates but let us take a look at the molecules to see what’s really going on

2. Collision Theory According the theory, atoms, molecules and ions must collide to react However, not all collisions produce reactions In order for a reaction to occur 1.Atoms, molecules, and ions must COLLIDE 2.Atoms, molecules, and ions must have CORRECT ORIENTATION 3.Atoms, molecules and ions must collide with sufficient ENERGY (ACTIVATION ENERGY) to form the activated complex and then the products

3. 2. If atoms, molecules, or ions do not have proper orientation there will not be a reaction http://www.mhh e.com/physsci/c hemistry/essent ialchemistry/flas h/collis11.swf

4. If proper orientation does occur an activated complex (aka transition state) is formed Activated complex = temporary, unstable arrangement of atoms that may form reactants or products

5. 3.The activation energy (E a ) determines if the activated complex will form the reactants or products. If there is enough energy to overcome the activation energy, products will form If there is not enough energy to cover the activation energy, reactants will from http://www.wwnorton.com/college/chemistry /gilbert2/chemtours.asp

6. Energy Diagrams Energy 

7. Energy Diagrams Exothermic –Energy is released –Products will have lower energy than reactants Endothermic –Energy is absorbed –Reactants will have lower energy than products

8. See if you can label the following parts of this energy diagram. Also, classify as endo or exo. A = reactants B = activated complex C = activation energy D = products Exothermic A C B D

9. To sum it all up… Collision Theory 1.Must collide 2.Must collide w/ correct orientation 3.Must collide w/ correct orientation & activation energy exothermic endothermic