Jess Tauber: Feb. 23, 2010
Henry Bent wrote:
`H and He are the only atoms whose cores contain no electrons.'
Given the truth of this, might this not be the basis of some sort of two-step offset for the entire system, i.e. an organizational principle for later derived behaviors?
Henry Bent: Feb. 23, 2010
STATEMENTS REGARDING ATOMIC CORES AND PERIODIC TABLES
Atoms of elements in a block's row have isoelectronic atomic cores.
Atoms of elements in a block's column have isoelectronic valence-shells or at least, in the d- and f-blocks, valence-shells that have the same number, if not exactly the same types, of valence-shell electrons about cores that have isoelectronic outer-shells.
Each block row of which there are 22 for Z through 120 represents a distinctive type of core.
With increasing Z across a block's rows, valence-shell electrons become increasingly core-like electrons.
On exiting a block, the core/valence-shell transformation is complete.
Cores are not isoelectronic across periodic tables' periods. They change from block to block, as well as from row to row within blocks.
Sizes of atomic cores provide numbers for creation of numerical indices of elements' distinctiveness that track closely the manner in which textbooks discuss the chemistries of the elements.
ATOMIC CORES ARE WHAT PERIODIC TABLES ARE ABOUT.
The elusive and mysterious "basic substances" that philosophers of the periodic table speak of are nothing more, nor less, than atoms' cores.
Atomic cores' three most important properties in chemistry are
o Type(s) of Valence-Shell Electrons
The angular quantum number of orbitals of an atom's predominant type of differentiating electrons is equal to the ordinal number of the atom's block when blocks are arranged by size, starting at ordinal number 0 for the 2-column block.
The radial quantum number of orbitals of differentiating electrons is equal to the ordinal numbers of the rows of the atoms within their blocks.
Cores of atoms related by primary kinships have the same charge and the same types of valence-shell electrons. Both conditions rule out grouping H with F and He with Ne.
Cores of atoms related by secondary chemical kinships have the same charge but not, predominantly, the same types of valence-shell electrons.
Cores of atoms related by tertiary chemical kinships have in their valence-shells the same number of vacancies.
Atomic numbers of cores of a Groups' elements 2, 3, and 4 and 4, 5, and 6 form primary "triads". Never is a Group's first element a member of a primary triad.
H and He are the only atoms whose cores contain no electrons.
In bond diagrams symbols of nonmetallic elements stand for the elements' atomic cores. That identification was made by G. N. Lewis, in 1916, when he identified the valence-stroke as 2 electrons and introduced, also, the concept of lone-pairs.
In chemical species that can be represented satisfactorily by bond diagrams, the atomic cores C+4, N+5, O+6, and F+7 obey an "Octet Rule". Their valence-shells are occupied by 8 electrons.
Valence-shells of cores of congeners of Octet-Rule-satisfying cores may contain 10 and 12 electrons, as in, e.g., PF5, PF6-, SF4 and SF6.
Lone-pairs in the valence-shells of large cores of large charge occupy more space about the cores than do bonding pairs and may become, in the presence of "good leaving groups", "inert pairs", yielding larger cores of lower charge (by 2 units), as, e.g., in PbCl2 and TlCl.
Atomic cores of nonmetals are small cations. The cations M+1, M+2, and M+3 of Groups I, II, and III are large atomic cores.
The step-like line that divides metals from nonmetals in periodic tables occurs at core radii equal to approximately 50 pm.
ATOMIC CORES ARE A LARGE PART OF WHAT CHEMISTRY IS ABOUT.
Jess Tauber: Feb. 22, 2010
If element 120 turns out to be a `noble' element, and if 120 is the end of the periodic system, then from the perspective of the 2D triangular modification of the Left Step PT, with all the numbers aligned, then this would be a symmetrical arrangement, 120 mirroring Helium, both being in the `alkaline earth' group.
Jess Tauber: Feb. 22, 2010
This from the English Wikipedia entry on element 120:
Unbinilium should be highly reactive, according to periodic trends, as this element is a member of alkaline earth metals. It would be much more reactive than any other lighter elements of this group. If group reactivity is followed, this element would react violently in air to form an oxide (UbnO) and in water to form the hydroxide, which would be a strong base and highly explosive in terms of flammability. It is also possible that, due to relativistic effects, the element has noble gas character, as already seen for element 114. A predicted oxidation state is II.
Does the inert pair effect, or relativistic stabilization with higher s, interact with these trends??
Jess Tauber: Feb. 22, 2010
What I find interesting is that the general trend for Aufbau anomalies is that they push towards lower QN l. f contributes to d, which then at least for element 103 contributes to p. Do we have any hints for p>s at the highest atomic numbers?
s is supposed to be the donor for 6 and 7d blocks, bypassing 4 and 5f. But is this true? Could it be possible that a relay is nearer the truth (that is, s>f>d)? The net effect would be no change for the f blocks, as electrons are themselves indistinguishable. That we don't find any s>f by itself is perplexing, just purely from a systemic point of view.
Also, things ain't as perfect in the p-block as one might think. I grabbed the following from the the English language Wikipedia entry on Element 118:
Ununoctium is a member of group 18, the zero-valence elements. The members of this group are usually inert to most common chemical reactions (for example, combustion) because the outer valence shell is completely filled with eight electrons. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound. It is thought that similarly, ununoctium has a closed outer valence shell in which its valence electrons are arranged in a 7s2, 7p6 configuration.
Consequently, some expect ununoctium to have similar physical and chemical properties to other members of its group, most closely resembling the noble gas above it in the periodic table, radon. Following the periodic trend, ununoctium would be expected to be slightly more reactive than radon. However, theoretical calculations have shown that it could be quite reactive, so that it can probably not be considered a noble gas. In addition to being far more reactive than radon, ununoctium may be even more reactive than elements 114 and 112. The reason for the apparent enhancement of the chemical activity of element 118 relative to radon is an energetic destabilization and a radial expansion of the last occupied 7p subshell. More precisely, considerable spin-orbit interactions between the 7p electrons with the inert 7s2 electrons, effectively lead to a second valence shell closing at element 114, and a significant decrease in stabilization of the closed shell of element 118. It has also been calculated that ununoctium, unlike other noble gases, binds an electron with release of energyor in other words, it exhibits positive electron affinity.
Ununoctium is expected to have by far the broadest polarizability of all elements before it in the periodic table, and almost twofold of radon. By extrapolating from the other noble gases, it is expected that ununoctium has a boiling point between 320 and 380 K. This is very different from the previously estimated values of 263 K or 247 K. Even given the large uncertainties of the calculations, it seems highly unlikely that element 118 would be a gas under standard conditions. And as the liquid range of the other gases is very narrow, between 2 and 9 kelvins, this element should be solid at standard conditions. If ununoctium forms a gas under standard conditions nevertheless, it would be one of the densest gaseous substances at standard conditions (even if it is monatomic like the other noble gases).
Because of its tremendous polarizability, ununoctium is expected to have an anomalously low ionization energy (similar to that of lead which is 70% of that of radon and significantly smaller than that of element 114) and a standard state condensed phase.
Valery Tsimmerman: Feb. 22, 2010
My response to a previous comment by Philip Stewart.
you are absolutely right when you say that, because of such elements as Cr, Cu, La and other odd balls that fall out of Afbau order, it is hard to make periodic table absolutely regular by mimicing electron configurations and quantum numbers. However, evey time you get to the alkaline earth metals regularity gets restored! Regularity gets restored even before, in p-block. Electron configurations of alkaline earth metals are PERFECT. Their atomic numbers perfectly match modified terahedral numbers, the numbers that can be arrived at by adding only spheres in odd rows and multiplied by two. I find it interesting that such regularity is violated (sometimes immediately, as in case of La and Ac), as soon as you leave alkaline earth group. That tells me something about special status, or completeness, of alkaline earth atoms.
Jess Tauber: Feb. 20, 2010
More odd mental gymnastics (not quite up to the level of numerology, I expect):
If one looks at the trends of neutron numbers as one increases atomic number, one finds that the ratio gets to be about 1.5 for n/p, at least around 120 (estimated).
For uranium 238, the percentage of n vs. total nucleon numbers is 0.6131453, close to the golden ratio number 0.6180339. Using the latter number instead to estimate how many neutrons element 120 `should' have, one gets 314.164, or just over 100 pi.
Looks like material reality is having a big laugh at our expense?
Jess Tauber: Feb. 20, 2010
Yes, Helium has unusual placement properties simply because the system is just starting to cumulate, and there aren't any p-block positions yet to backstep 2 moves to.
Are there any other numerically derivative relationships like this? Knight's moves? Aufbau anomalies (I know the causal explanations given by chemists, the question is whether there is any more regular, simple equational setup that will give the same results)?
In linguistics we run into similar issues- where one process has to run its course entirely before we can then make modifications based on finished products (that is, secondary and tertiary effects require a substrate to work on). Sometimes hierarchically lower level productions aren't entirely completed before they get modified, and this results in unexpected complexity and irregularity- competing motivations, and creation of choice. This is one way languages change.
It makes me wonder whether the properties of the periodic system are fixed in stone, or may vary. We know that overt element properties can change in different physical regimes of pressure, temperature, and I'd guess also magnetic and electrical fields, etc. What about spacetime itself (which can be stretched or shrunk), or neutrino flux? In such situations, are changes entirely predictable, or can the systems coexist in two or more states, as in quantum superpositions? What determines which dominates? Just local energy, or something more, as in long-distance (how about temporally disjunct as well) entanglements? There may be a lot more negotiation going on than we know about.