Theoretical chemistry is a sub field of chemistry which involves the application of physics in chemistry to predict and also to explain chemical phenomena. Theoretical chemistry has previously mainly consisted of quantum chemistry which is the use of quantum mechanics for solving problems in chemistry. This field is primarily divided into dynamics, electronic structure and statistical mechanics. In predicting chemical reactivities, all of these fields are applied to various degrees. There are many other research areas in theoretical chemistry such as chemical kinetics and mathematical chemistry. Although, much of theoretical chemistry often comes under computational chemistry but this term often refers to applying theoretical chemistry in a specified setting accompanied with few approximation methods such as force field methods, density functional theory, post Hatree-Fock or semi-empirical methods such as PM3. Statistical mechanics are also applied by some chemical theorists in order to bridge the gap between the macroscopic vast characteristics of systems and the quantum microscopic phenomena.

Theoretical chemistry term papers are typically written in ACS writing style which is the official referencing style of American Chemical Society. However, other writing styles may also be used depending upon the word limit and other such paper requirements. Theoretical research papers often seem to be focusing upon a single branch of theoretical chemistry at one time. For example, theoretical chemistry research papers may focus upon quantum field theory within quantum chemistry. Other branches of theoretical chemistry include molecular dynamics, molecular modeling and mechanics, theoretical chemical kinetics and mathematical chemistry.