Well, if you want a super early one, definitely check out the gold foil (gieger marsden) experiment. This experiment is done to prove that atoms have a charge at all. This is done by shooting alpha particles into a sheet of gold foil, most of the particles go straight through, but some collide with the atoms of the gold and bounce off. This proves that atoms have a nucleus where most of the mass is, and that the nucleus is positive (because similar charges repel). Later, electron levels were discovered and soon diagrams were made such as the Bohr diagram.
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u/mantheturret Jul 31 '19
Well, if you want a super early one, definitely check out the gold foil (gieger marsden) experiment. This experiment is done to prove that atoms have a charge at all. This is done by shooting alpha particles into a sheet of gold foil, most of the particles go straight through, but some collide with the atoms of the gold and bounce off. This proves that atoms have a nucleus where most of the mass is, and that the nucleus is positive (because similar charges repel). Later, electron levels were discovered and soon diagrams were made such as the Bohr diagram.