Periodic Table |
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| What is the Periodic Table Showing? | Periodicity |
The INTERNET Database of Periodic Tables
There are thousands of periodic tables in web space, but this is the only comprehensive database of periodic tables & periodic system formulations. If you know of an interesting periodic table that is missing, please contact the database curator: Mark R. Leach Ph.D. The database holds information on periodic tables, the discovery of the elements, the elucidation of atomic weights and the discovery of atomic structure (and much, much more).
Periodic Tables from the year 1927 :
| 1927 | Le Roy's Periodic Table |
| 1927 | Fifth Solvay Conference on Physics |
| Year: 1927 | PT id = 1015, Type = formulation |
LeRoy's Periodic Table
R.H. LeRoy, Teaching the Periodic Classification of Elements, School Science and Mathematics 1927, 27: 793-799. This formulation thulium in group IC and has the actinides in the C groups, analogous to the lanthanides, two decades before Seaborg.
René adds:
"This 1927 formulation has several remarkable features.
"The lighter and heavier lanthanides and actinides are shown in numbered C groups i.e. C4, C5, C6, C7 and C1, C2, and C3. The 14 remaining elements between C7 and C1 are labelled as transition elements, analogous to the old chemistry notion of the ferromagnetic and platinum metals in IUPAC groups 9 to 11 being labelled as transition elements. There is no known Tm(I) although this would not be inconceivable. Nd is in group C6, which doesn't quite work since there is no Nd(VI) although such an oxidation state is not inconceivable given the existence of Pr(V). in group C7, Pm(VII) is not known. For the actinides, Md(I) has been reported but not confirmed.
"B-Al-Sc-Y-La-Ac are shown as main group metals; that would be consistent with their chemistry. While Sc-Y-La-Ac are routinely classified as transition metals their chemistry is largely that which would be expected of main group metals following the alkaline earths in IUPAC group 2.
"The author refers to the noble gases as 'transitional'. The noble gases bridge the most reactive groups of elements in the periodic table – the alkali metals in group I and the halogens in group VII. That's a concept that's rarely referred to these days even though it's still quite valid.
"Ga-In-Tl are shown as B3 metals, falling just after Zn-Cd-Hg in group B2, and Cu-Ag-Au in group B1. That doesn't work for Ga etc, which are nowadays regarded as main group metals.
"H is shown floating above the A elements, and in the transitional zone, with links to F and to Li."

Thanks to John Marks for the tip, and to René for the comments/analysis!
| Year: 1927 | PT id = 1377, Type = structure |
Fifth Solvay Conference on Physics
"The most famous conference was the fifth Solvay Conference on Physics, which was held from 24 to 29 October 1927. The subject was Electrons and Photons and the world's most notable physicists met to discuss the newly formulated quantum theory. The leading figures were Albert Einstein and Niels Bohr. Seventeen of the 29 attendees were or became Nobel Prize winners, including Marie Skłodowska-Curie who, alone among them, had won Nobel Prizes in two separate scientific disciplines. The anti-German prejudice that had prevented Einstein and others from attending the Solvay conferences held after the First World War had melted away. Essentially all of those names who had contributed to the recent development of the quantum theory were at this Solvay Conference, including Bohr, Born, de Broglie, Dirac, Heisenberg, Pauli, Planck, Lorentz, Compton, Ehrenfest, and Schrödinger. Heisenberg commented:
"Through the possibility of exchange between the representatives of different lines of research, this conference has contributed extraordinarily to the clarification of the physical foundations of the quantum theory. It forms, so to speak, the outward completion of the quantum theory."
"The photo taken of this conference's participants is sometimes entitled 'The Most Intelligent Photo Ever Taken', for its depiction of the world's leading physicists gathered together in one shot."

A. Piccard, E. Henriot, P. Ehrenfest, E. Herzen, Th. De Donder, E. Schrödinger, J.E. Verschaffelt, W. Pauli, W. Heisenberg, R.H. Fowler, L. Brillouin;
P. Debye, M. Knudsen, W.L. Bragg, H.A. Kramers, P.A.M. Dirac, A.H. Compton, L. de Broglie, M. Born, N. Bohr;
I. Langmuir, M. Planck, M. Skłodowska-Curie, H.A. Lorentz, A. Einstein, P. Langevin, Ch. E. Guye, C.T.R. Wilson, O.W. Richardson
Fifth conference participants, 1927. Institut International de Physique Solvay in Leopold Park.
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| What is the Periodic Table Showing? | Periodicity |
© Mark R. Leach Ph.D. 1999 –
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