I've read about Rutherford's gold foil test that moved us from the plum pudding model of the atom, but... how do they know the specifics of the atoms? I understand the nucleus and electrons around it but how do they know how many electrons are around the nucleus? How do they know the energy level of the electrons? How do they know that there are neutrons in the nucleus if they're electrically nuetral?
Sorry, this is kind of all-encompassing but I'm just confused how they know this stuff without a huge microscope to look and count the electrons.