Origins of the Ambiguity of the Current Definition of Chemical Element

Abstract

The current (IUPAC) definition of “chemical element” has two parts. The first part describes a concept on which chemists generally agreed when important aspects of the structure of chemical substances became clear by the middle of the twentieth century; the second part concerns a concept which had been important in “the chemical revolution” of the late eighteenth century—but which is not consistent with the definition first given. Although long familiarity has made the internal inconsistency of this “dual definition” of chemical element nearly undetectable by chemical professionals, that lack of clarity still causes major difficulty for logically minded beginning chemistry students. The concept of chemical element described in the second part of the current IUPAC definition has long been obsolete; it should now be abandoned. Retention of an obsolete definition for an important concept is characteristic of what John Dewey called “unmodern philosophy.”