Bohr announced the idea of the electron orbits around the nucleus, opposed to having the electrons in the nucleus.
Major discovery by Dalton: atoms were the smallest, most basic unit of matter. Indivisible into smaller parts.
JJ Thomson's 'Plum Pudding Model' of the atom, a sphere of positive charge containing electrons within the nucleus.
Rutherford's discovery of the nucleus and the development of the nuclear model of the atom.
This is a Ted-Ed Talk by Theresa Doud. She discusses the quest for the atom has been a long one, beginning 2,400 years ago with the work of a Greek philosopher and later continued by a Quaker and a few Nobel Prize-winning scientists.
This link describes the parts of an atom and their importance to the structure.