App
Carolina Biological Supply

Building Atoms, Ions, and Isotopes HD

For Students 7th - 12th
Atomic theory, a periodic table, and a place to practice making atom models without having to draw every proton, neutron, electron, and orbital! This resource is colorful, visually pleasing, and easy to use. 
Interactive
Concord Consortium

Concord Consortium: Stem Resources: Excited States and Photons

For Students 9th - 10th
Students are able to explore the effects of energy on excitation of atoms through simulations, then relate this information to photons at atoms' absorption and emission of light. Multiple-choice and short answer questions are found...