One may ask the question, “Do atomic nuclei have internal electron orbitals having similarities to those believed to exist in molecules? A quick answer could be, “Why not? There seems to have been little attention given to the idea of there being atomic orbitals in atomic nuclei. Although the ideas of molecular orbitals is used in both organic chemistry and inorganic chemistry, the ideas apparently have not been extended to nuclear chemistry.
There may be at least two reasons for this. The first reason is that apparently no-one has done the math. to compare size/density information about the electron and the proton such as to realize that the much smaller, and far more dense electron should be able to pass quite freely through protons and would have space for movement within a proton. The second reason would be the fixation on the idea that neutrons, as such, exist in nuclei. If neutrons, as such, exist within atomic nuclei, then, electrons, as such, do not; therefore, there would be no need to consider the concept of electron orbitals within nuclei. If there are no electrons, the idea of orbitals does not occur. Instead there has developed a theory of neutron shells, exchange forces, strong nuclear forces and weak nuclear forces. It seems quite likely that a concept of Nuclear Orbitals for electrons, could account for much of what these forces are said to do.
[As an aside, the writer wonders why the term, “force,” is used in this type of argument,considering that there is the old rule that “each and every force is accompanied by an equal and opposite force.” These so-called “forces” do not fit this rule.]
To start looking at the idea of orbitals. let us first look at the ideas of Molecular Orbitals. “MOs.” In particular, as the ideas are applied to the chemistry of Carbon, “Organic Chemistry.” Much of the chemistry of Carbon may be correlated to “three kinds of Carbon.” These three are, as follows:
1.Tetrahedral Carbon, “single-bonded Carbon,” which has four things bonded to a Carbon atom at 120 degree angles, in three-dimensional space, this is called, “sp3-hybridized ” Carbon. (The terminology will be explained later.) The solid form of Carbon with this structure is diamond.
2, Trigonal Carbon, “double-bonded Carbon,” called “sp2,” with three bonds at 120 degrees in a plane, has electron orbital(s) above and below the plane. the solid form of carbon with this structure is graphite, which exists in flat, slippery sheets.
3. Linear Carbon, “triple-bonded Carbon, called, “sp1.” has a linear, cylindrical structure. This form is not found in solid Carbon, but occurs in many compounds. Some of the best known of these are Acetylene, H-CC-H; Carbon Dioxide, O=C=O, Carbon Monoxide, CO, and Hydrogen Cyanide, HCN, all of which are liner, cylindrical molecules.
It seems logical that, at the level of the nucleus, we would find these same three basic shapes to occur among the simpler atoms. Deuterium, composed of two protons and two electrons, would be expected to have an ovoid, “egg-shaped” nucleus, that is, a cylinder rounded off. Tritium. composed of three protons and three electrons, and its “Iso-3,3-set” partner, Helium, isotope three, He3, would be expected to have nuclei which were either of the tetrahedral form, or of the trigonal form as a flat triangle.
In another article, not yet writien, focuslng more on shapes, the writer intends to explain why he feels that a tetrahedral form, analogous to the form of Ammonia, NH3, is probably the usual case for Tritium, while the flat triangle is more likely the case for Helium 3.
The normal situation for Helium 4, the common isotope of Helium, would be a tetrahedron. At very low temperatures, the nucleus may change to a flat, square planar structure. (See, A guide to Helium II) Let us return to the nomenclature and explain the “s,” “p.” notation used above. These take their names from the lowest electronic orbitals considered to belong to the Hydrogen atom. The “s” orbital, which takes its name from the “sharp” spectral lines of the Hydrogen spectrum, is felt to be a simply sphere, the “p,” orbitals, named for the “principal” lines of the Hydrogen spectrum, is thought to consist of three “dumbbell” shaped orbits at 90 degrees to each other,
Combining the one “s” orbit with but one of the “p” orbits is considered to give two orbits with principal lobes opposite to one another in a given atom. The remaining “p” orbitals, extending out from the line can combine with other “p” orbitals, if two atoms are joined together to form a set of two “Pi” bonds making a cylinder of electron motions about the line connecting the two atoms.
With “sp2, ” we have three orbitals at 120 degrees and one possible Pi bond, or set of bonds, which are taking up the space above and below the plane of the other three bonds. In molecules, we consider two electrons in an orbital to comprise a bond. The “sp3” simply has four bonds to the central nucleus, using eight electrons, none of them considered to be free to move other than between/around more than two centers in a “Sigma” bond. In nuclei, it appears that, at least in some cases, only one electron may be necessary to bond two or more centers.
We have been discussing the ideas of electrons moving in various patterns in molecules, concentrating on the three simple shapes found in Carbon chemistry. Of course, there are far more complex patterns possible, and in nuclei, it can be expected that patterns will get complicated very rapidly; however, the point that is trying to be made here is that, if electrons can be considered to be holding together atoms in molecules by their motions about atoms, why is it not reasonable to think that the same thing would not be true for holding protons together in nuclei? The very heavy, but very huge (in comparison to the electron) protons would seem to be easier to be held together by electrons moving about and through them than would be the case for atoms being held together in molecules.
It seems to make more sense to see the difference between the Neutron and the Hydrogen atom to be a case of the electron’s motion being within the Neutron.and both within and outside the nucleus of the Hydrogen atom, than to have no real correlation between the two entities which could be considered “stereo-isomers.” That is, things made up of the same two basic units arranged differently in space. (See, A guide to the neutron: Facts and Fables)
For the Deuterium atom and the Hydrogen molecule to be bonded by electrons perhaps between the two protons in the case of H:H and within the two protons in the Deuterium seems also to be logical. In molecules, molecular orbitals are considered to involve two or more atoms, that is to say, two or more centers. By the same reasoning, the first unit that one might wish to discuss as possessing true nuclear orbitals would be the Deuterium atom, “the Hydrogen Isotope of mass two.”
This is generally considered as having a nucleus made up of one proton and one neutron. If we consider it in a nuclear-orbital fashion we would consider it as being composed of two protons bonded by one electron in something analogous to the “Sigma ” bond assumed to hold the two atoms together in the Hydrogen molecule. However, one might suggest that considering the difference in geometry and charge distributions, that the case may be much closer to the situation seen in Acetylene where there is possibility of the electrons moving about not only between the carbon atoms but above, below and completely around.
In the Deuterium nucleus electrons would be free to move anywhere within the two bonded protons as well as any space between them and around them. Also, as no electron would have a label “valence electron” or “nuclear electron” a very complex electron “dance” can be visualized. [It would be interesting to see if some computer programmer could work up something on this idea. ] “Spin” data on the Deuterium atom indicate that there are two “unpaired” electrons. ( “Spin” generally correlates to “unpaired electrons” with a spin of “1/2” indicating one unpaired electron, spin of “1′” indicating two, spin 3/2 is three and so on.) Deuterium has a “Spin number of !” indicating two unpaired electrons. By a Nuclear Orbital approach this makes sense, one in the nucleus, one in the “valence shell.” The conventional model would have no real explanation.
Another support for the idea of “NOs” is magnetic moment data, which is related to electrical asymmetry. The neutron, Hydrogen atom and the Deuterium atom all have magnetic moments. What is interesting in that the neutron and the Deuterium atom have magnetic moments that are listed as being “negative.” Hydrogen1 has a positive magnetic moment. In the view we are using, we can correlate a negative magnetic moment to the presence of unpaired electrons within the “nucleus” of the Neutron and the Deuterium atom and the positive magnetic moment to the ‘”external ” valence electron of the H1 atom. This magnetic moment correlation appears again at He3 which also has a negative magnetic moment and, in our reasoning, an unpaired electron bonding three protons together in a flat.triangular nucleus.
The fact that Tritium has no magnetic moment despite having one electron in an outer orbit, as opposed to the Helium 3 having two is the reason that the writer feels that the Tritium nucleus would be a vibrating tetrahedron with the three protons changing places among the four possible tetrahedral positions, such an array would not have a net magnetic moment whereas the flat array visualized for He3 would. The two, are, of course, “stereo-isomeric” members of the “Iso-3,3-set,” differing in their shape, energy content and electronic distributions.
[The “Iso-x,y-set” notation is the author’s own invention as to a way of grouping together molecules, ions, atoms, having the same numbers of electrons, “x” and protons, “y.” ” Iso-1,0-set” would be the electron. Iso-0,1-set is the proton. Iso-1,1-set would include the electron and proton considered as a pair, the neutron, and H1…] This article, discussing the possibility of there being Nuclear Orbitals within atomic nuclei has moved somewhat into what probably should be a related article discussing the possible significances of nuclear geometries.
In summary, the possibility of nuclear orbitals and their significance for nuclear chemistry seems to have been overlooked. This author strongly suggests that the idea be seriously examined.
