Elements, Compounds, and Other Chemical Kinds

In this paper I assess the problems and prospects of a microstructural approach to chemical substances. Kripke and Putnam famously claimed that (a) to be gold is to have atomic number 79, and (b) to be water is to be H2O. I relate (a) to the concept of element in the history of chemistry, arguing that the reference of element names is determined by atomic number. Compounds are more difficult: water is so complex and heterogeneous at the molecular level that ‘water is H2O’ seems false. I sketch a response to this problem