As new, modern images of the structure of the atom were discovered one critical discovery was that the atom was not uniform in density. Mass and charge were not uniformily distributed thoughout the atom, but strangely concentrated in certain regions.

In which of the following links is there a discussion of the discovery of mass-concentration within the atom, and how this discovery was made?

Alpha rays were important tools used by scientists to discover the ways in which atoms are contstucted. But alpha rays are hard to catch and hold.

In which of the following links is a method described whereby alpha rays can be trapped, and then their properties studied?

Max Plank had a problem. The probability of radiation taking place from a black body actually decreased instead of increasing as the frequency of radiation increased. This was contrary to all expectations

In which of the following links does Max Plank solve this problem by proposing a radical new idea?

Electrons surrounding the atom are only to be found in very specific volumes of space - at least most of the time! These volumes of space have very characteristic shape, but why are they this shape and not other?

In which of the following links is the special 3-D shape of the electron orbitals discussed and the reasons explained?