Photo: Niels Bohr's research notes for his new atomic theory Rutherford's find came from a very strange experience. Everyone at that time imagined the atom as a "plum pudding." That is ...

Bohr began to work on the problem of the atom's structure. Ernest Rutherford had recently suggested the atom had a miniature, dense nucleus surrounded by a cloud of nearly weightless electrons.

Though this "Bohr model" of the atom is now considered relatively simplistic compared to the detailed diagrams we have now, 111 years after its inception, it is still used to introduce students to ...