Editing Mendeleev's predicted elements (section)

== Prefixes ==
To give provisional names to his predicted elements, [[Dmitri Mendeleev]] used the prefixes ''[[wikt:१#Sanskrit|eka]]''- {{IPAc-en|ˈ|iː|k|ə|-}},{{refn|group=note|name=ekasanskrit|refn=Citing from the 1871 article:<ref name="mendeleev1871">{{cite journal|last1=Mendeleev|first1=D.|title=The natural system of elements and its application to the indication of the properties of undiscovered elements|journal=Journal of the Russian Chemical Society|date=1871|volume=3|pages=25–56|url=https://www.knigafund.ru/books/56718/read#page31|access-date=23 August 2017|language=ru|archive-date=13 August 2017|archive-url=https://web.archive.org/web/20170813142644/https://www.knigafund.ru/books/56718/read#page31|url-status=dead}}</ref>{{rp|45}}<br />{{lang|ru|Элементъ этотъ предлагаю предварительно назвать 'экаборомъ', производя это названіе отъ того что онъ слѣдуетъ за боромъ, какъ первый элементъ четныхъ группъ, а слогъ 'эка' производится отъ санскритскаго слова, обозначающаго 'одинъ'. Eb{{=}}45. Экаборъ ...}}<br />I propose that this element be called ''ekaboron'' first, producing this name from the fact that it comes after the boron, like the first element of even groups, and the syllable ''eka'' is derived from a Sanskrit word that stands for ''one''. Eb=45. Ekaboron ...
}} ''[[wikt:२#Sanskrit|dvi]]''- or ''[[wikt:dwi-#English|dwi-]]'', and  ''[[wikt:३#Sanskrit|tri]]''-, from the [[Sanskrit]] names of digits 1, 2, and 3,<ref>{{Cite journal|arxiv=physics/0411080v2|last1=Kak|first1=Subhash|title=Mendeleev and the Periodic Table of Elements|journal=Sandhan|volume=4|issue=2|pages=115–123|year=2004|bibcode=2004physics..11080K}}</ref> depending upon whether the predicted element was one, two, or three places down from the known element of the same [[group (periodic table)|group]] in his table. For example, [[germanium]] was called eka-silicon until its discovery in 1886, and [[rhenium]] was called dvi-[[manganese]] before its discovery in 1926.

The ''eka-'' prefix was used by other theorists, and not only in Mendeleev's own predictions. Before the discovery, [[francium]] was referred to as ''eka-caesium'', and [[astatine]] as ''eka-iodine''. Sometimes, eka- is still used to refer to some of the [[transuranic element]]s, for example, ''eka-[[radium]]'' for [[unbinilium]]. However, the current official [[IUPAC]] practice is to use a [[systematic element name]] based on the [[atomic number]] of the element as the provisional name, instead of being based on its position in the periodic table as these prefixes require.