Quantum chemistry seeks to predict and explain phenomena from a large number of domains including (among others): chemistry, physics, biology, chemical engineering, and materials science. The unifying theme of most quantum chemistry techniques is that the system being modeled is described with atomic resolution, i.e., the model accounts for individual nuclei and electrons. In practice, quantum chemistry then goes on to define a number of other concepts such as atoms (the combination of a nucleus with electrons), molecules (a set of atoms), and chemical systems (a molecule plus its environment). Chemist is charged with providing robust, performant, abstractions for concepts commonly encountered in quantum chemistry.