History of Atoms
There are a few highlights of atomic history that every teacher covers, so those are the ones you'll find in the videos below.
Plum Pudding Model of Atoms
Up until the late 1800's, scientists starting with Dalton thought there were these tiny things called atoms that were the smallest anything could be. Around 1900 experiments started showing the existence of electrons, then protons. The puzzle was, how do you get a bunch of protons that repel each other to co-exist in an atom? Enter the reasonable, but ultimately incorrect, Plum Pudding theory.
Rutherford's Gold Foil Experiment
This particular experiment is covered by every chemistry teacher because it invalidated the plum pudding model and demonstrated that an atom's protons are all together in a clump. If your teacher is the type to ask a short answer question on tests, this could be the one.
Bohr's Model of the Atom
The basis of quantum mechanics, Bohr's model created the concept of energy levels in the atom, where each electron is in either one orbital or another but never in between. It explains much of the behavior of atoms, and is the basis of more advanced topics such as emission and absorption spectra, as well as electron configurations.