We investigate a pattern of isotopes with the highest isotopic abundance, the number of nucleons of some stable isotopes tends to A=S(S+1)-2, this means that S is probably the number of shells. Therefore, we propose a nucleon arrangement model that can include all magic numbers. Furthermore, based on some simple patterns in atomic nuclei, such as shell structures, magic numbers, magnetic moment and collective modes, we developed a toroidal helical wave orbital model to explore the microstructure of isotopes that matches the proposed arrangement pattern.