All 84 electronic states of Na-2 that correlate adiabatically to separated atom limits up to Na(3s)+Na(5p) have been relabeled according to the dominant hydrogenic nl lambda characters of the Rydberg orbital and classified as core-penetrating vs core-nonpenetrating states. This labeling and classification scheme establishes a unique correspondence between experimentally observed and theoretically predicted electronic states, which provides insights into the electronic structure of Na-2. Hydrogenic nl lambda labels for Rydberg states are of particular value for predicting and interpreting transition strengths, sensitivity to external electric fields, and surprisingly disparate collisional properties for nearly isoenergetic states.