The underlying chemistry refers to the fundamental chemical processes or reactions that occur within a system, which ultimately determine its properties and behavior. Full definition
Whatever the underlying chemistry of it all, it seemed to work: the cake rose really well. (tinandthyme.uk)
«The purpose is to understand the underlying chemistry of the element. (sciencedaily.com)
To my adviser, the unexpected failure of the technique I was using offered a chance to dig deeper into the underlying chemistry. (science.sciencemag.org)