Describe why Br2 is more selective than Cl2 in a radical addition
- The rate determining step is when the radical C is created from the radical halogen
- This is an exothermic rxn for Cl2, but an endothermic rxn for Br2
- Since it is endothermic the transition state is actually closer to the products than reactants and will resemble them more (Hammond's Postulate)