**4. Results**

The results presented in this paper are narrowed to the three aspects of the structure of 100Sn with an idea of demonstrating the role of like-nucleon vs. proton-neutron coupling in the *g*9/2 shell (see Figure 1). First, the evolution of excited states was examined along the *N =* 50 line describing seniority in a *g*9/2<sup>n</sup> and simple level coupling *g*9/2*p*1/2. Additionally, a JUN45 calculation and, even larger model spaces when available, are presented. Second, the *N=Z* line is analyzed below 100Sn where the shape change is expected along the *g*9/2*<sup>n</sup>* orbital configuration. The recent developments in nuclear structure above *N =* 50 is summarized in the last subsection.
