The gallery of failed atomic models, 1903-1913 from Skulls in the Stars.

[H]ow many atomic models were there?

A lot. Most people in physics are taught Thomson’s ‘plum pudding’ model of the atom, but a little investigating turned up no less than eight distinct pictures of atomic structure.

The late 1800s and early 1900s was the breakthrough period of atomic research. A number of tantalizing pieces of experimental evidence suggested a nontrivial internal structure to the atom.

We are taught (and teach) the Bohr model because it has some use, even though it is wrong/incomplete. But it’s useful to remember that in the presence of fragmentary information there are going to be failed attempts at explaining the underlying phenomenon. As more data is uncovered the false theories can be weeded out, because they will not have predicted the event or will have predicted a phenomenon that was never observed, despite a reasonable expectation of doing so.