Is the Nucleus Fundamental?

Again, periodicity of nuclear properties...
       mass, decay cascades, etc.
suggest that nucleons fill quantum shells,
       just like electrons in the outer regions of atom

...look at chart of nuclei

Scientists found the nucleus composed of nucleons:

• neutrons (n) discovered by Chadwick (1932)
• and protons (p)

only differ in electric charge, mass (m_n>m_p)

• held together by (residual) strong force
• broken apart by the weak force

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