  The scope of this paper is to discuss the major works that appeared in the
period of 1904 to 1913: atomic models proposed by Thomson and Hantaro Nagaoka
(1904), Rutherford (1911), and Bohr (1913), and the experimental work that
motivated them. It will be seen that, although all of the models discussed here
were later shown to be incorrect or incomplete, each one represented an
essential step towards an understanding of the nature of matter, a view of the
physical world often taken for granted a century down the road.
