The aim of the present paper is to analyze the problem of the relationship between
chemistry and physics, by focusing on the widely discussed case of the atomic orbitals.
We will begin by remembering the difference between the physical and the chemical interpretation
of the concept of orbital. Then, we will refer to the claim made in 1999 that
atomic orbitals have been directly imaged for the first time. On this basis, we will analyze
the problem from a new approach, by comparing the concept of orbital used in physics with
the concept of orbital used in chemistry. Such an analysis will allow us to argue for an ontological
pluralism that admits the coexistence of different ontologies without priorities or
metaphysical privileges. From this philosophical framework, the concepts of chemical orbital
and physical orbital correspond to two different ontologies. As a consequence, chemical orbitals
are real entities belonging to the ontology of molecular chemistry, and can be observed
like any other entity not belonging to the quantum mechanical ontology.
