Atom basics:
http://www.chem4kids.com/files/atom_structure.html

Early Ideas about Atoms
http://galileo.phys.virginia.edu/classes/252/atoms.html


John Dalton's Atomic Theory
http://www.iun.edu/~cpanhd/C101webnotes/composition/dalton.html

JJ Thomson and the Electron
http://www.chemheritage.org/classroom/chemach/atomic/thomson.html


Rutherford and Bohr Break the "Plum Pudding" Model
www.pbs.org/wgbh/aso/databank/entries/dp13at.html


Chadwick and Rutherford and the Neutron
www.pbs.org/wgbh/aso/databank/entries/dp32ne.html

History of the Atom Timelinehttp://atomictimeline.net/index.php