Considering the plan of the nuclear-force interaction of nucleons, the atomic nucleus can be presented consisting of blobs-nucleons of the identical size equal to the size of a neutron.

As inside of a nucleus of property of neutrons and protons are equalized and also all of them are equally crossly drawn, the nucleus should be sphere with peak a close-packed arangement of nucleons.

In geometry given 3-dimensional packing of balls for a long time is known, and is termed - rhombohedral. In it each ball adjoins at once with 12 adjacent.
It is gained by consecutive superimposition against each other layers from the most dense flat packings balls which can be figured:

so: or so:

Thus, at superimposition, each new layer is displaced so, that its balls have got in dimples of the inferior layer.

Pay attention, that bias probably double. Owing to it, at rhombohedral packings are interesting property:
- If bias from a layer to a layer will iterate the same, we shall gain a crystalline lattice.
- If it is chaotic, not crystalline packing, but all the same - also most dense of all possible will be gained.

The formula of dependence of the size of a nucleus from amount of nucleons in it at rhombohedral packing looks like:
R   - radius of a nucleus;
a   - distance centre to centre the next balls-nucleons;
A   - amount of nucleons.
If in the formula to substitute the size of a neutron, the formula in precision will coincide with known semiempirical.

According to this formula, the heaviest for today chemical element Uuh (the nuclear number 116, nuclear mass 292) has only 7,3 nucleons in diameter.