Which experiments prove atomic theory?
atoms have: nuclei; electrons; protons; and neutrons.
That the number of electrons atoms have determines their relationship with other atoms.
That the atom is the smallest elemental unit of matter - that we can't continue to divide atoms into anything smaller and have them retain the characteristics of the parent element.
That everything is made of atoms.
These sub-theories might spur more thoughts of individual experiments that prove individual sub-atomic theories (my guess is more was able to be proven after more experiments followed).