Elementary Reaction:This term refers to a single process within multi-step reactions which occurs in one step. It's like sprinting straight from start to finish without any hurdles or obstacles.
Pre-Equilibrium Approach: This concept assumes that faster steps reach equilibrium before slow steps occur. It's like our fastest runner finishing their leg and waiting for others before moving on.
Consecutive Reactions: These are series of reactions where product of one reaction becomes reactant for next one. It’s like passing baton in relay race – each runner completes their part then hands off responsibility to next person.