Editing Extended periodic table (section)

===Kulsha===
Computational chemist [[Andrey Kulsha]] has suggested two forms of the extended periodic table up to 172 that build on and refine Nefedov et al.'s versions up to 164 with reference to Pyykkö's calculations.<ref name=primefan/> Based on their likely chemical properties, elements 157–172 are placed by both forms as eighth-period congeners of yttrium through xenon in the fifth period;<ref name=primefan/> this extends Nefedov et al.'s placement of 157–164 under yttrium through palladium,<ref name=nefedov>{{cite journal |last1=Nefedov |first1=V.I. |last2=Trzhaskovskaya |first2=M.B. |last3=Yarzhemskii |first3=V.G. |title=Electronic Configurations and the Periodic Table for Superheavy Elements |journal=Doklady Physical Chemistry |date=2006 |volume=408 |issue=2 |pages=149–151 |doi=10.1134/S0012501606060029 |s2cid=95738861 |issn=0012-5016 |url=http://www.primefan.ru/stuff/chem/nefedov.pdf}}</ref> and agrees with the chemical analogies given by Fricke et al.<ref name=actrev/>

Kulsha suggested two ways to deal with elements 121–156, that lack precise analogues among earlier elements. In his first form (2011, after Pyykkö's paper was published),<ref name=primefan/> elements 121–138 and 139–156 are placed as two separate rows (together called "ultransition elements"), related by the addition of a 5g<sup>18</sup> subshell into the core, as according to Pyykkö's calculations of oxidation states,<ref name=PT172/> they should, respectively, mimic lanthanides and actinides.<ref name=primefan/><ref name=sicius>{{cite book |last=Sicius |first=Hermann |author-link= |date=2021 |title=Handbuch der chemischen Elemente |language=de |url= |location= |publisher=Springer |page=1085 |isbn= |quote=Kulsha nennt die 36 Elemente zwischen 121 und 156 „Ultransition Elements“ und schlägt vor, sie in zwei Serien aufzuteilen, in eine von 121 bis 138 und eine zweite von 139 bis 156. Die erste ähnelte eher den Lanthanoiden (Seltenerden), die zweite mehr den Actinoiden.}}</ref> In his second suggestion (2016), elements 121–142 form a g-block (as they have 5g activity), while elements 143–156 form an f-block placed under actinium through nobelium.<ref name=dications/>
[[File:Pt172.svg|center|512px|thumb|Kulsha's first suggested form]]
[[File:Pt172expanded.svg|center|1024px|thumb|Kulsha's second suggested form]]
Thus, period 8 emerges with 54 elements, and the next noble element after 118 is 172.<ref name=wothers>{{cite book |last=Wothers |first=Peter |author-link= |date=2019 |title=Antimony, Gold, and Jupiter's Wolf |url= |location= |publisher=Oxford University Press |page=vii |isbn=978-0-19-965272-3 |quote=It’s possible that other elements might be synthesized—research is certainly ongoing—but it’s unlikely that the table will ever appear as neat again, since to fill the next row, another fifty-four elements would need to be made.}}</ref>