Harmonic Symmetry of the Proton Skeleton and a Structural Interpretation of Isotope Stability: The Symmetric Skeleton Structure (SSS) Approach

In this study, the internal structure of the atomic nucleus is analyzed within the framework of the Symmetric Skeleton Structure (SSS) approach, and a structural relationship between the harmonic symmetry of the proton skeleton and isotope stability is proposed. In classical nuclear models (the shell model, the liquid-drop model, and collective and deformed nuclear models), isotope stability is mainly explained through energetic minima, shell closures, and the concept of “magic numbers.” The proposed SSS approach emphasizes that the nucleus should be analyzed not only in energetic terms but also in terms of its geometric and mechanical structural organization. In the SSS model, protons are organized as a symmetric skeleton arranged in concentric layers from the center of the nucleus toward the periphery. The correspondence of these layers to specific harmonic sequences directly affects the distribution of proton–proton Coulomb repulsion and the character of the structural voids available for neutron accommodation. In particular, the structure of the equatorial layer plays a decisive role in the intranuclear mechanical balance. An even number of protons in the equatorial layer creates structurally “softer” conditions for neutron accommodation and broadens the isotope stability interval.