The Structure of Chemical Particles

The possibility of predicting on a purely theoretical basis the existence of some “elementary” particles composing chemical particles (atoms, molecules) is studied. For this purpose the notion of Fock theories in separable Hilbert spaces is introduced. By using the mathematical structure of Fock theory—which is a nontrivial generalization of the Fock space—the notion of particle as sharp entity is defined. It is proved that chemical changes cannot be described by those Fock theories, which consider particles as sharply defined entities. This is a consequence of quantum-mechanical dynamical postulate concerning time evolutions of conservative systems. Finally it is shown that a category of Fock theories may describe changes in the number of chemical particles during conservative evolutions. This result is naturally obtained if the hypothesis about existence of some “elementary particles” composing chemical particles is accepted. Another simultaneously obtained conclusion is that chemical particles involved in chemical processes cannot be sharply defined.