A chemical reaction is a method that manages the chemical transformation of one set of chemical substances to another classically, chemical reactions include changes that only include the positions of electrons in the forming and breaking of chemical bonds within atoms, with no change to the nuclei (no change to the elements present), and can frequently be explained by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of volatile and radioactive elements where both electronic and nuclear variations can occur.
Chemical reaction engineering is a specialization in chemical engineering or industrial chemistry dealing with chemical reactors. Frequently the term associates specifically to catalytic reaction systems where either a homogeneous or heterogeneous catalyst is present in the reactor. Sometimes a reactor per se is not present by itself, but preferably is combined into a process, for example in reactive divisions vessels, retorts, certain fuel cells, and photocatalytic surfaces. The issue of solvent effects on reaction kinetics is also estimated as an integral part.