Reasons to doubt microstructural essentialism about chemical elements

Essentialist theories of natural kinds, widely discredited by philosophers of the life sciences, remain an important focal point in recent philosophy of chemistry. Within that literature, one popular position is that gold, hydrogen, and the other members of the periodic table are observer-independent and objectively delineable kinds, each defined by their essential property of discrete nuclear charge. This is 'microstructural' essentialism about chemical elements, the core claim of which in the modern setting is that nuclear charge determines the properties of elements and the substances they constitute. In this paper, I aim to demonstrate that detailed attention to the empirical relationships between nuclear charge, atomic species, and chemical substances provides reasons to doubt microstructural essentialism about chemical elements.