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.
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Correlation of Electron Affinity (F) with Elemental Orbital Radii (rorb)
From Jour. Fac. Sci., Hokkaido Univ., Ser. IV. vol. 22, no. 2, Aug., 1987, pp. 357-385, The Connection Between the Properties of Elements and Compounds; Mineralogical-Crystallochemical Classification of Elements by Alexander A. Godovikov & Yu Hariya and expanded by René Vernon who writes.
René Vernon writes:
I was delighted to read about two properties that account for nearly everything seen in the periodic table.
While researching double periodicity, I happened upon an obscure article, which simply correlates electron affinity with orbital radius, and in so doing reproduces the broad contours of the periodic table. Having never thought much about the value or significance of EA, and its absence of easily discernible trends, I was suitably astonished. The authors left out the Ln and An and stopped at Bi. They were sitting on a gold mine but provided no further analysis.
I added the data up to Lr, updated the EA values, and have redrawn their graph. It is a thing of beauty and wonderment in its simplest sufficient complexity and its return on investment. I've appended 39 observations, covering all 103 elements.
- Very good correspondence with natural categories
- Largely linear trends seen along main groups; two switchbacks seen in group 13; also falloffs (6p sub-shell) seen in groups 14-17
- First row anomalies seen for Li (in amphoteric territory), Be (ditto), C (misaligned), N (in noble gas territory), O (misaligned), F (ditto) and He (ditto)
- For group 13, the whole group is anomalous, no doubt due to the scandide contraction impacting Ga and the double whammy of the lanthanide and 5d contraction impacting Tl
- Nitrogen was called a noble gas before the discovery of the real noble gases and appropriately enough falls into that territory
- Rn is metallic enough to show cationic behaviour and falls just outside of noble gas territory
- F and O are the most corrosive of the corrosive nonmetals
- The rest of the corrosive nonmetals (Cl, Br and I) are nicely distributed, across the border from F
- The rest of the simple and complex anions, funnily enough, comprise the intermediate nonmetals
- The metalloids are nicely aligned; Ge falls a little outside of the metalloid line, being still occasionally referred to as a metal; Sb, being the most metallic of the metalloids falls outside the border; At is inside; Po is just outside
- Pd is located among the nonmetals due to its absence of 5s electrons; see here
- The proximity of H to Pd is astonishing given the latter's capacity to adsorb the former
- The post-transition metals (PTM) form an "archipelago of amphoterism" bounded by transition metals: Ni and C to the west; Fe and Re to the south; V, Tc and W to the east; noble metals to the north
- Curiously, Zn, Cd, and Hg are collocated with Be, and distant from the PTM and the TM proper (aside from Mn)
- Zn is shown as amphoteric, which it is. Cd is shown as cationic but is not too far away from amphoteric territory; it does show amphoterism, reluctantly; Hg is shown as amphoteric which is the case, weakly, for HgO, as is the congener sulfide HgS, which forms anionic thiomercurates (such as Na2HgS2 and BaHgS3) in strongly basic solutions
- The ostensibly noble metals are nicely delineated; Ag is anomalous given its greater reactivity; Cu, as a coinage metal, is a little further away
- The proximity of Au and Pt to the halogen line is remarkable given the former's capacity to form monovalent anions
- The ferromagnetic metals (Fe-Co-Ni) form a nice line
- The TM from groups 4-12 form switchback patterns e.g. Ti-Zr and the switchback to Hf
- The refractory metals, Nb, Ta, Mo, W and Re are in a wedge formation
- Tc is the central element of the periodic table in terms of mean radius and EA values; V is close, Cr is a little further away
- Ti is just inside the basic cation line; while Ti(IV) is amphoteric, Ti3+ is ionic
- Sc-Y-La shows a main group pattern up to La, when there is a switchback to Ac
- Sc-Y-Lu-Lr shows a TM switch back pattern
- La, and to lesser extent Ce are rather separated from the rest of the Ln, consistent with Restrepo and here.
- Sc and Lu are close to the amphoteric territory and are both in fact, weakly amphoteric
- The post-cerium Ln and An (but for Th) all fall within basic cation territory
- EA values for the An are estimates and need to be treated with due caution
- The light actinides (Th to Cm) occupy a tight locus, with the exception of Th, where the 5f collapse is thought to occur, and Pu, which sits on the border of 5f delocalisation and localisation
- While the light actinides U to Cm are shown as being cationic they are all known in amphoteric forms
- The heavy actinides, Bk to Lr, are widely dispersed
- All the Ln, bar Tm, are located within close proximity of the light An locus; Tm is the least abundant stable Ln
- The gap between La and Ce, and rest of the Ln is consistent with Restrepo's findings and here
- Nobelium in this edition of the chart falls off the bottom, having a radius 1.58 (cf Es) and an EA of -2.33
- There is an extraordinary alignment between He and the Group 2 metals
- Magnesium is on the cationic-amphoteric boundary; some of its compounds show appreciable covalent character
- Li, being the least basic of the alkali metals, is located just outside the alkalic zone; Li compounds are known for their covalent properties
- The reversal of the positions of Fr and Cs is consistent with Cs being the most electronegative metal
- A similar, weaker pattern is seen with Ba and Ra.
So there it is, just two properties account for nearly everything.
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© Mark R. Leach Ph.D. 1999 –
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