Nucleus Structure

Atomic Nucleus, Nucleons and the Tetrahedron

The atomic nucleus is composed of nucleons (protons and neutrons). The arrangement of these nucleons, in particular protons, is considered in this section and the section on orbital shapes as the arrangement directly affects the sequence of the Periodic Table of Elements, the orbital shapes, and the quantum leaps of the electron to various energy levels.

Before the nucleus structure is proposed, tetrahedral numbers are revisited since the structure appears to be based upon a tetrahedral structure. Tetrahedrons are geometric 3D stability for waves in all directions. The properties of a tetrahedron: the layer height, the number in each layer and the total number is shown in the figure below.  The important number for this section is the number in each layer. These have been mapped to subshells: s, p, d and f which will be discussed in the orbital shapes section.

Tetrahedral Numbers

Tetrahedral Numbers


This tetrahedral structure is further explained and related to the atomic element sequence from the Periodic Table of Elements. In addition to orbital shapes, this structure also explains the transitions of s, p, d and f blocks.  The rules of nucleon stacking explain the sequence in the periodic table: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p which are circled in red in below.

Periodic Table of Elements – Annotated Marking Sequence Completion

Periodic Table of Elements – Annotated Marking Sequence Completion 


Nucleon Stacking Rules

A set of rules was established for nucleons (protons and neutrons) stacking in an atomic nucleus to match the sequence of the Periodic Table of Elements and also meeting the proton fill order for orbital shapes.  Each of these rules is ultimately a result of the fundamental rule that subatomic particles that form these composite particles (nucleons) move to minimize wave amplitude.

  1. Nucleons arrange from the center first, then outward.
  2. A neutron may replace a proton (in the proton’s position), but not vice versa, due to proton separation rules.
  3. Each level fills the easiest proton spin first, which is the same spin direction as the atom (it takes less energy/wave amplitude). Then, the opposite spin direction is filled.
  4. Protons first form a linear structure (1s), then planar structure (2s), before building in three dimensions in a tetrahedral structure (2p).
  5. After the first complete tetrahedron (2p), the nucleons build symmetrically – a second tetrahedron.
  6. Nucleons maintain a required proton to neutron (p->n) and proton to proton (p->p) separation rule.



The Nucleon Stacking Legend shows a legend of nucleon stacking in the upcoming models that will be presented.  A proton is represented in red and neutron in blue color. To reduce complexity viewing the models, only neutrons that replace a proton are shown. In the atomic nucleus, neutrons separate protons at required distances. These separation neutrons are not shown in the models to simplify the diagrams, although an example is provided in the legend.  A neutron can also take a proton’s position. These protons will be shown in the models because they are required to complete a tetrahedral row.

Only the side view of the atomic nucleus is shown in the models. Using the tetrahedron numbers from above, it is easy to decipher how many total nucleons are in each row despite what is shown in the side view. For example, a second-level tetrahedron shows two nucleons in a side view, yet there is a total of three nucleons (the third is positioned behind the first two). This is also illustrated in the legend.

Nucleon Stacking Legend

Nucleon Stacking Legend   




Nucleon Stacking – 1s to 3d Orbitals

Using the aforementioned nucleon stacking rules and legend, a model of the atomic nucleus from 1s to 3d was established. The periodic table sequence corresponds to a completion of a row in the tetrahedral-based structure. Argon (Ar) shows an example of completing a stable tetrahedral structure, but using a neutron in the place of a proton. This is validated by the fact that argon (Z=18) has the same nucleon count as calcium (Z=20) as noted by the atomic mass units (amu).

Nucleon Stacking from 1s to 3d Atomic Elements (He to Zn)




Nucleon Stacking – 4p to 4f Orbitals (potential arrangement)

The nucleon stacking model was continued through the first f orbital (Hg), although the variations and possibilities for symmetry become more complex. Thus, these models are potential arrangements that match the nucleon stacking rules to keep symmetry and stability in the nucleus when it corresponds to the end of a block sequence.

Nucleon Stacking from 4p to 4f Atomic Elements (Kr to Lu)



Video Summary