Talk:Electron configuration

Exceptions to the Aufbau principle
The d-block exceptions to the Aufbau principle are admirably dealt with in this article. However, I noticed that apart from a passing reference to Lawrencium, none of the Lanthanoid or Actinoid elements are discussed, despite the fact that the electron configurations periodic table quite clearly lists numerous exceptions which cannot be explained away as easily, since they do not result in a half-full shell. Does anyone know of a simple reason why this occurs? Should these exceptions be mentioned in the article even if the reason is unknown? Thanks, Rundquist (talk) 01:42, 18 July 2008 (UTC)
 * The whole idea of half-filled subshells being related to the anomalies is junk, actually. (Eric Scerri has made this point.) It is neither necessary (Nb has one, no half-filled d subshell) nor sufficient (W could get a half-filled d subshell by copying Cr and Mo, yet it doesn't). The only thing it has going for it is its ubiquity in chemistry texts and courses that sweep everything past the first row under the rug (except sometimes Ag, which doesn't falsify the idea by itself). In actuality the reason comes from subtle electron-repulsion effects (it is correctly explained in Feynman's lectures on physics). You have to do some serious work to calculate it, though; and all for not much benefit because you will then find that the energy differences are small enough that in a chemical environment they don't matter. Double sharp (talk) 03:45, 15 February 2021 (UTC)

Noble gas configurations are stable
In the case of Og, probably not so. Problem is large spin-orbit splitting effects: 7p splits strongly into a more stable 7p1/2 part and a less stable 7p3/2 part. Therefore practically the atom rather has four loosely bound electrons significantly above an inert flerovium core, and acts like Sn, which is hardly that noble. At least according to predictions.

I am not sure how to make it correct without jumping into off-topic pedantry, though. Perhaps one could simply say that for the first six noble gases, the general inertness is experimentally known (since Og has not yet been experimentally studied). Double sharp (talk) 03:52, 13 February 2021 (UTC)


 * The other noble gases are of course not completely inert either, and the reactivity increases gradually with atomic number. At Noble gas we do say that "The reactivity follows the order Ne < He < Ar < Kr < Xe < Rn ≪ Og." And at Oganesson we mention the large spin-orbit splitting and its expected effects. So here we can link to those articles for more detail. For example, we can just say "Oganesson is predicted to be more reactive". Full stop and the interested reader can follow the link. Dirac66 (talk) 17:43, 26 February 2021 (UTC)
 * OK, added a sentence "Oganesson is predicted to be more reactive due to relativistic effects for heavy atoms." Double sharp (talk) 07:10, 14 April 2021 (UTC)

Chemistry
What are chemical compound 41.210.146.239 (talk) 16:57, 23 June 2022 (UTC)
 * See article Chemical compound. In Wikipedia it helps to go to the correct article. Dirac66 (talk) 18:09, 23 June 2022 (UTC)