This document discusses the foundations of chemical kinetic modeling and reaction models. It outlines the key pillars of knowledge required, including general chemistry, thermodynamics, chemical kinetics, and quantum chemistry. It then describes the step-wise process for constructing detailed chemical kinetic models, including determining elementary reactions, estimating thermo-chemical data and rate coefficients, validating models experimentally, and applying the models to reactor scale-up and design. Reactor scale-up requires satisfying similarity parameters between small and large-scale systems. The goal is to develop accurate predictive models and design safe, commercial-scale chemical reactors.