Some aspects of the metaphysics of chemistry and the nature of the elements

There is now a considerable body of published work on the episte- mology of modern chemistry, especially with regard to the nature of quantum chemistry. In addition, the question of the metaphysical underpinnings of chemistry has received a good deal of attention. The present article concen- trates on metaphysical considerations including the question of whether ele- ments and groups of elements are natural kinds. It is also argued that an appeal to the metaphysical nature of elements can help clarify the re-emerging con- troversies among chemists regarding the placement of the elements hydrogen and helium in the periodic system and the question of whether there exists a best form of the periodic table.