Wikipedia talk:WikiProject Elements/IUPAC definition for transition metals

IUPAC definition for transition metals

NOTE: This section is transcluded so the widest-possible number of people can comment

I've been auditing the nav images in element articles to fix wrong neutron counts and giving Lu and Lr the lanthanoid and actinoid coloring, respectively. Part way through, I started to review our definitions for element categories to check them against IUPAC's provisional recommendations. See IUPAC Red Book IR-3.6 GROUPS OF ELEMENTS. Turns out that their specific definition for transition metal deviates from ours in a somewhat embarrassing way:

• IUPAC defines transition metals specifically as being those elements in groups 3 to 11. This excludes the group 12 elements!

ED NOTE: Turns out, that IUPAC's approved recommendations define transition metals as either the set of elements in groups 3 to 12 (our current set-up) or the set of elements from 3 to 11 (the set-up in the below table).

Fixing this results in somewhat modified periodic tables (Note, that the expanded 'Other metal' category includes all the post-transition metals plus aluminium):

Table showing the more IUPAC consistent element categories

So, before I finish my audit and fix of the nav images, I'd like to know if I should fix group 12 to be consistent with the provisional IUPAC definition of transition metals. OR should we wait for IUPAC to come out with the final-updated Red Book (comment period ends at the end of 2008)? I'm putting my audit and update of the nav images on hold until we figure this out. --mav (talk) 17:50, 5 October 2008 (UTC)

I am not sure how many agree to this definition so waiting would be ok. Nergaal (talk) 18:10, 5 October 2008 (UTC)

I just checked one of my college chemistry textbooks and it agrees with IUPAC. If this definition for transition metals is already widespread, then we may not need to wait for IUPAC's final revision of the Red Book. On the other hand, the updated document may impact other parts of the table and / or nav images. I'm simply not sure how or when we should proceed. --mav (talk) 18:18, 5 October 2008 (UTC)

Erm, the comment period ended in 2004, according to the root of the file you quoted. The text approved in 2005 was (p. 51):

The elements (except hydrogen) of groups 1, 2 and 13–18 are designated as main group elements and, except in group 18, the first two elements of each main group are termed typical elements. Optionally, the letters s, p, d and f may be used to distinguish different blocks of elements. For example, the elements of groups 3–12 are the d-block elements. These elements are also commonly referred to as the transition elements, though the elements of group 12 are not always included; the f-block elements are sometimes referred to as the inner transition elements.

As far as I'm aware, there are no new inorganic recommendations planned for four or five years or so (until they get round to sorting out inorganic Preferred IUPAC names). Physchim62 (talk) 18:25, 5 October 2008 (UTC)

Ah - I saw this and assumed it also applied to the inorganic nomenclature. My bad. I also remember something about unfilled d-suborbitals as part of the definition, which also excludes group 12 elements (with a complication with at least one Hg compound). --mav (talk) 18:35, 5 October 2008 (UTC)

Definition of this term has always been a problem- whether to base the classification on chemistry or atom electron configuration. I was taught at school (1942 Sherwood Taylor text book) that the transition metals did not include Cu group and Zn group - only then to be told at university that Cu was a transition metal. IMO we should go with current IUPAC - that definition has been around for at least 40 years (Cotton and Wilkinson 2d edition 1966)- it leaves a little problem of colouring in and explaining the position of Zn group which is neither main group nor transition metal, but is in the d block according to our chart- although the chart conflicts with the definition in the article (sic "..highest energy electron is in a d orbital") which would seem to exclude both copper (3d10 4s1) and zinc (3d10 4s2) - if our list of electron configurations is right. Best of luck.--Axiosaurus (talk) 08:32, 6 October 2008 (UTC)

The current IUPAC definition (quoted above) gives us freedom to include group 12 or not. Let's not forget that Cotton & Wilkinson doesn't class scandium and yttrium as transition metals either, on chemical grounds. Greenwood and Earnshaw agrees with our current classification except for lanthanum and actinium, which they (correctly in my view) class as transition metals. I seem to remember that the edition of Sherwood Taylor that you quote classes thorium and uranium as transition metals and, in the case of thorium ([Rn] 7s² 5d²), a naive or dogmatic application of the electron configuration criterion would force us to do the same! Physchim62 (talk) 08:52, 6 October 2008 (UTC)

IMHO IUPAC does not clearly define the matter, that's why such a long discussion is needed. My experience is very close to the Axiosaurus' one. The first simple definition refers to empty d orbitals at the elemental state whereas at university I was taught that it's more useful to include group 11 (Cu, Ag, Au) as well because they form ions having empty d orbitals - that is the Cotton Wilkinson definition. This is supported by their behaviour, for instance because they can form coloured complex as the other transition metals. I've never heard that the 12th group (Zn, Cd, Hg) can be included in the transition metals because their behaviour, i.e as catalist, is completely different than the others due to their full d shell. Most of my teachers would have marked as a serious mistake. Cotton Wilkinson (III edition, 1972) includes Scandium and Yttrium between the transition metals. Chemical behaviour should prevail as even Mendeleev based and actually built the periodic table on this characteristic. Some authors try to bridge this describing group 3-12 as d block. Please do not be misled by the shape of the periodic table or, worse, by aestetics issues. Chemistry is an experimental science and sometimes cannot be oversimplyfied. --Avogadro-I (talk) 22:46, 24 November 2008 (UTC)

I've always thought that our periodic tables have too many colors and that we could save ourselves a lot of trouble if we got rid of most of them. But I'm afraid I'm in the minority. --Itub (talk) 10:46, 6 October 2008 (UTC)

But the table is so purty with the colors! And we'd have one less thing to argue about discuss - that would be boring. ;) --mav (talk)

Great feedback - thanks for finding the the current recommendations. Looks like IUPAC is giving us some leeway in the definition of transition metals in the approved recommendations. That means that our current table does not conflict with IUPAC. That is all I was worried about. We should therefore leave well-enough alone. We can revisit this if/when IUPAC comes up with a more rigorous definition. But I welcome anybody else to comment just in case we have missed anything. Again - Thank you everybody! --mav (talk) 01:03, 7 October 2008 (UTC)

Yes, my own opinion is that it's one of those debates that creates more heat than useful work! Physchim62 (talk) 01:21, 7 October 2008 (UTC)

And don't forget that Wikipedia:Naming conventions (chemistry) allows us to go againt IUPAC occasionally, when circumstances demand it! Physchim62 (talk) 01:27, 7 October 2008 (UTC)

It looks like I may be getting in here a little late, but I just wanted to note that in post-transition metal, it claims that the IUPAC definition for transition metals is in conflict with it self. Based upon what I've read here, that doesn't seem to be the case any more. I think it needs to be cleaned up to match the above conclusions. --Wizard191 (talk) 02:04, 8 October 2008 (UTC)

Just a note: first time we get the chance, we should try to get rid of the color differenciation between actinoids and lanthanoids. Nergaal (talk) 17:22, 15 October 2008 (UTC)

Why and what would replace it? --mav (talk)

does not add enough information, and within the TMs, the variations in chemistry are larger than those between Ac and Ln's. Any of the two colors used now would be fine, or some random mix of the two too. Nergaal (talk) 15:16, 19 October 2008 (UTC)

The actinides and lanthanides are distinct enough for us to label them as separate element categories. That combined with the lack of consensus on what is an inner transition tells me that we should leave well enough alone. --mav (talk) 01:06, 20 October 2008 (UTC)

Mercury is considered a transition element under both IUPAC definitions now, because the compound HgF₄ has been synthesized in 2007, giving Hg a d⁸ electron configuration. Should this be incorporated in the table and the article? Kumorifox (talk) 13:46, 18 May 2009 (UTC)

Not everyone agrees that mercury is a transition metal due to the observation of HgF4 under exotic conditions. See the article on HgF4 for details. --Itub (talk) 01:12, 19 May 2009 (UTC)

Removing suggestion to Merge d-block and Transition metal

Well I showed up 3 months too late for the fun, but I based on what I read, I am removing the suggestion to merge these two articles. No change in IUPAC recommendations will ever alter Periodic table (by blocks). The blocks must have a number of columns corresponding to the number of electrons that a full subshell can hold. So the d-block must occupy groups 3-12. This is a man-made oversimplification because the chemistry and even the ground state electrons in Periodic_table_(electron_configurations) are messier than the blockiness, but that's ok. Oversimplifications are important because they make reality interesting. "Transition metal" on the other hand, is a convention, not an oversimplification. One bunch of folks call some elements "Transition metals" and another bunch of folks don't, and IUPAC says that's ok. When the most recent IUPAC book says "the elements of group 12 are not always included," they mean not always included in the transition metals. Group 12 has to be in the d-block because if it weren't, then the d-block would only hold 9 columns, meaning 9 electrons maximum in the d-subshell and Kimmie, the cute new 22-year old high-school chemistry teacher, would cry because even the oversimplifications would be too complex to teach, and angry mobs of high school boys who love Kimmie would grab torches and pitchforks and attack IUPAC folks and Wikipedia editors for making Kimmie cry. So that's why d-block and Transition metal should not be merged even though IUPAC says they -can- contain the same elements. By the way, Inner transition element and f-block should also be separate articles for the same reason. Conventions and oversimplifications are very, very different. Flying Jazz (talk) 07:47, 18 January 2009 (UTC)

I agree and I'm glad to see you editing again. :) --mav (talk) 15:40, 19 January 2009 (UTC)

Well, if Kimmie is wrong, too bad I say. (^_^) Other than that, I agree they should remain separate articles (though that's probably because I am of the firm opinion that the d-block and the transition metals should be different groups). Double sharp (talk) 04:52, 15 September 2013 (UTC)