Rutherford's Gold-Foil Experiment
Onion the Omniscientist: Ernest E. Rutherford performed his Gold-Foil Experiment, basing his inferences on the Plum Pudding Model, which led to the discovery of the nucleus and neutrons.
Clueless Cat: Wow, gold?! How exactly did this experiment work?
Onion the Omniscientist: Well, first, with a radioactive source, he shot alpha particles at a thin piece of gold foil.
Clueless Cat: Umm... What exactly are alpha particles?
Onion the Omniscientist: Good question! They're basically just helium nuclei, which are positively charged.
Clueless Cat: Oh! Okay then what happened after he shot alpha particles at the gold foil?
Onion the Omniscientist: Well... According to the Plum Pudding Model, it was expected that they would mostly pass directly through the gold foil with little or no deflection. Instead, they noticed that although the majority of the alpha particles did just that, there were actually some alpha particles that either deflected in the direction it came from or at really large angles.
Clueless Cat: That really rocked the world of science, didn't it?
Onion the Omniscientist: Why yes, it did! Rutherford described this unexpected outcome “as if you had fired a 15-inch [artillery] shell at a piece of tissue paper and it came back and hit you.”
Clueless Cat: WOW! That is pretty surprising! What did he actually infer from this bizarre occurrence?
Onion the Omniscientist: Rutherford actually figured out quite a few things. He inferred that there must be very strong particles that reflected the alpha particles. Yet, they had to be extremely small since only a tiny fraction of the alpha particles were affected by it. He also inferred that the area of these particles had to be densely compacted with a positive charge, which he named the nucleus.
Clueless Cat: Those inferences have told us a lot about atoms now, right? So was there another idea updated about the atom? Maybe... like neutrons?
Onion the Omniscientist: Exactly! He inferred that neutrally charged particles, which he called neutrons, were a part of the nucleus because the protons’ mass wasn’t equal to the atomic mass, but they still kept the atom neutral. So all was good.
Clueless Cat: But where would the electrons go?
Onion the Omniscientist: Very observant! Although he couldn’t come up with an answer, he proposed that electrons surround the nucleus.
Clueless Cat: Well, that means atoms can no longer be compared to the Plum Pudding model! So it was disproved!
Onion the Omniscientist: That's right!
