Eric Scerri (University of California, Los Angeles) - The dual sense of the term ‘element has attracted a great deal of attention from contemporary philosophers of chemistry. Roughly speaking one sense of the term refers to Lavoisier’s element or simple substances that can be isolated. Secondly, there is a more ancient metaphysical concept of an element as a bearer of properties. The second more abstract sense was revived by Mendeleev while he arrived at his views on chemical periodicity. According to Mendeleev, the latter view is needed to understand the sense in which simple substances exist in their compounds. For example, sodium the well-known light grey and reactive metal does not exist, as such, in the compound sodium chloride. Mendeleev would claim that sodium is still present in the metaphysical sense of the element. My presentation will consist of an examination of some ongoing debated issues over the dual sense of ‘element.’ The following questions will be explored. 1. Are the two senses of element co-extensive or is one contained within the other? 2. What properties, if any, other than atomic number (or atomic weight in Mendeleev’s time) do elements in the more general abstract sense possess? 3. To what extent did Lavoisier abandon the abstract sense of elements while promoting his more positive sense of elements as simple substances? 4. Just how abstractly should Mendeleev’s sense of element be regarded? 5. Should the distinction be regarded macroscopically or microscopically? 6. Does Paneth’s account of the distinction confuse the issue of the abstract sense of element with combined element? 7. To what use did Mendeleev put his sense of element in the course of discovering his version of the periodic table? 8. How is the change from using atomic weight as the ordering principle for the elements, that occurred in the 1920s, connected with the two senses of the concept of element?
