Describe the atomic structure and the evidence for its existence.

Here is the completed account concerning atomic theory:

The nucleus of an atom contains nearly all the mass of the atom and is surrounded by electrons in energy levels. Although it is not possible to see atoms, clusters of about one hundred atoms can be seen under an electron Microscope, every student of chemistry believes that they exist. Nuclear bombs have been exploded, so this is the Atomic age or the nuclear age, or maybe by now we have moved on to the IT age!