Chem4kids
Chem4 Kids: Atoms
This site provides a detailed overview of atoms. Content explores an atom's structure, as well as what ions are, how atoms bond, what compounds are (including how to name compounds), and what isotopes are.
PBS
Nova: Atom Builder
Find out if you know enough about atoms to build them. The goal of the activity is to build an atom of a particular element by dragging the correct numbers of neutrons, protons and electrons into the atom.