How fast a reaction goes versus how far — reaction-coordinate diagrams, activation energy, transition states and intermediates, the Hammond postulate, and what catalysis does and doesn't change.
Activation energy, transition states, and intermediates on the reaction coordinate
ΔG, ΔH, ΔS and thermodynamic vs kinetic control
The Hammond postulate and the rate-determining step
Rate laws, reaction order, and how catalysis works