User Tools

    To create and edit articles, please register and log-in

Main Menu : categories & index etc.

Main menu
Click categories to expand

A-Z listingplugin-autotooltip__plain plugin-autotooltip_bigA-Z listing

This is an alphabetical index of all content pages.

Other categories



Also see

Importance Ratings
Curator's rationale
AI Policy

Twitter feed 𝕏

Feeds + s.e.o. etc.
rss / xml feed
sitemap file
A-Z listing (archived)

Indexed under : Proposed Content

Wikenigma - an Encyclopedia of Unknowns Wikenigma - an Encyclopedia of the Unknown

Periodic Table standardisation

Note: This article is currently in the Proposed Content section.

The International Union of Pure and Applied Chemistry (IUPAC) publishes the one of the recognised global standards for the table of chemical elements.

But the layout of the Periodic Table, which groups chemical elements according to their electronic properties (i.e. free electrons), has not been universally agreed upon.

There are continuing disagreements about 'Group 3' (which, according to IUPAC, currently contains Scandium, Yttrium, Lanthanoids and Actinoids)

The question of precisely which elements should be placed in group 3 has been debated from time to time. An IUPAC project has been recently initiated to resolve the question. Will group 3 consist of Sc, Y, Lu, and Lr or, will it consist of Sc, Y, La and Ac?

In March 2021, IUPAC published a discussion document on the subject. For the time being, the official version is from 2018 - and some chemists refer to it as a 'compromise'.

Editor's note: This article seems more focused on lack of agreement about classification than 'unknowns' as such.

    Please share this page to help promote Wikenigma !

Dear reader : Do you have any suggestions for the site's content?

Ideas for new topics, and suggested additions / corrections for older ones, are always welcome.

If you have skills or interests in a particular field, and have suggestions for Wikenigma, get in touch !

Or, if you'd like to become a regular contributor . . . request a login password. Registered users can edit the entire content of the site, and also create new pages.

( The 'Notes for contributors' section in the main menu has further information and guidelines etc.)

Automatic Translation

You are currently viewing an auto-translated version of Wikenigma

Please be aware that no automatic translation engines are 100% accurate, and so the auto-translated content will very probably feature errors and omissions.

Nevertheless, Wikenigma hopes that the translated content will help to attract a wider global audience.

Show another (random) article

Further resources :