EŵpoweriŶg StudeŶts’ Understanding of the Atomic Shell Structure – Part 1 Shells, Subshells, and Orbitals B D C D D Dr. Renuka Rajasekaran Chemist and Chemistry Educator PhD (Chemistry); PhD (Chemistry Education) rekharajaseran@gmail.com The greatest problem in understanding the atomic structure is: the shell structure (ring diagram) and the orbital structure (box diagram), which remain disconnected. The concepts of subshells and orbitals are not effectively integrated either in the ring diagram or in the box diagram. Quantum numbers are treated as though they are extraneous to both diagrams. There is not enough emphasis at the fundamental level, on the fact that the shell structure forms the basis for the periodic table. Here is a simpler treatment of the atomic structure for the high school students and the early chemistry courses in college. This Part 1 in the Series. Progressive Chemistry Learning Series Volume 1, 2006, pp. 1-7.