how were alpha particles used and founded before the gold foil experiment if we didn’t know at that time that protons and neutrons existed and we didn’t know the charge of alpha particles

Question

I understood most of the rutherford experiment except how did rutherford know the properties of alpha particles when we didn’t know about protons and neutrons .

In: Chemistry

Answer 1

He invented the concept of a small core with most of the mass and positive charge to explain the results. That idea that that core was protons and neutrons came later. Not sure how much later though.