The first atom, Hydrogen, is one proton and one electron, and the next, Helium, has two protons and two electrons, but it also has two neutrons in its nucleus, and no-one knows why. Each higher element has not only another proton and electron, but also one or more neutrons, so:
“… all the stable nuclei have more neutrons than protons (or equal numbers), and the heavier nuclei are increasingly neutron-rich.” (Marburger, 2011), p254.
Current theories don’t explain why heavier nuclei need more neutrons to be stable (Figure 4.22). The shell model of electrons doesn’t work, because some nuclei aren’t spherical. The standard model doesn’t help either because if gluons hold the protons together, why are neutrons needed, and how do the gluons know how many neutrons to add to a heavy nucleus? That the nucleus is protons and neutrons sitting side-by-side, like fruits in a bowl, stuck together by gluon glue, predicts nothing.
However now suppose that the proton nucleus of a Hydrogen atom is a closed string of three quarks in a triangle, held together by photon sharing, as proposed earlier. This allows the triangle to open up and recombine in longer quark strings that satisfy the same rules, namely a closed string with the internal angles of an equilateral triangle.
That the Helium nucleus, of two protons and two neutrons, is one quark string held together by photon sharing, gives it a unity that particles in a bowl don’t have. In the fruit-bowl model, a Helium nucleus is four proton and neutron particles glued together but in this model it is one unified string of quarks, given only that each link bends the string 60º, so quarks must rotate to connect. Higher nuclei can then form in the same way.
Neutrons are then needed because positive protons repel, so they can’t come side-by-side to share photons, but neutrons can act as buffers. When the nuclear quark string forms, neutrons sit between same-charge protons that repel, which needs at least as many neutrons as protons, as observed (Figure 4.22). For example, a Helium nucleus of two protons needs two neutron buffers between the protons in the closed string.
Closed quark strings will also be compact and nearly spheres, as observed, and large nuclei may need more neutrons to avoid fold-back loci that happen to make protons adjacent. This evolution also explains why some shapes more stable:
“Nuclei with either protons or neutron equal to certain “magic” numbers (2, 8, 20, 28, 50, 82, 126) are particularly stable.” (Marburger, 2011), p253.
Atomic nuclei as closed quark strings will fold in space to form shapes as proteins do, and symmetric shapes are more stable, so the nuclei magic numbers are just those that produce symmetric shapes.
A quark string model then explains what the fruit bowl particle model doesn’t, namely why nuclei need as many neutrons as protons, why some need more, and why nuclei with a “magic” number of nucleons and more stable.