The “magic numbers” of the independent particle model show up clearly if you look closely at the detailed systematics of the curve of binding energy.

Niels Henrik David Bohr (1885 – 1962)

John Archibald Wheeler (1911 – 2008)

Carl Friedrich Freiherr von Weizsäcker (1912 – 2007)

George Gamow (1904 - 1968)

Hans Bethe (1906 - 2005)

Remember that molecules, atoms, and nuclei all have masses LESS than the summed total mass of the constituents, since the internal energy of a bound system is negative when we define the zero of energy as the state where all constituents are separated by an infinite distance. An atomic mass unit (symbolized  amu or au) is defined as precisely 1/12 the mass of an atom of ¹²C. Not used by nuclear physics!!