Chemical classification systems attempt to classify as
elements or
compounds according to certain chemical functional or
structural properties. Where as the structural properties are largely
intrinsic, functional properties and the derived classifications depend to a certain degree on the type of
chemical interaction partners on which the function is exerted. Sometimes other criteria like purely physical ones (e.g.
molecular weight) or - on the other hand - functional properties above the chemical level are also used for building chemical
taxonomies.