How did people calculate the mass and position of sub-atomic particles?
That is the scale of quantum mechanics. If you haven’t done quantum mechanics then don’t worry about it! Without it however atomic physics has gaping holes in it (I now realise that my entire chemistry education was founded on a huge load of simplifications). we calculate the mass when we split them up- so we can deduce an electron’s mass by ionising some sort of filament (ie. breaking electrons from atoms using a current), accelerating the free electrons through a field, and then measuring how much they deviate when we put them in a magnetic field. If the electron is heavy, it will deviate less, because a perpendicular force will cause a smaller acceleration on a heaiver particle. I think a similar thing happens for the proton. As for position, I think lattive spacing tells you a lot about this, and we can actually see atomic lattices using electron microscopes.
