Talk:Lanthanide

Lanthanide?

The USGS (on a subpage of the ref at the bottom of our article) says:

• The lanthanides are a group of 15 chemically similar elements with atomic numbers 57 through 71, inclusive. Although not a lanthanide, yttrium, atomic number 39, is included in the rare earths because it often occurs with them in nature, having similar chemical properties. Scandium, atomic number 21, is also included in the group, although it typically occurs in rare- earths ores only in minor amounts because of its smaller atomic and ionic size.

[emphasis added]

Our article talks of only 57 through 70, inclusive.

Any chemists able to clarify? Robin Patterson 21:51, 25 Jan 2005 (UTC)

There's no uniformly agreed-upon definition among chemists. There are three possible definitions: 57-70, 57-71, or 58-71. Without getting into lots of chemistry, suffice it to say there are arguments that can be made for each of these three.

The three definitions are reflected in different arrangements of the Periodic Table as well. Everyone agrees that 56 goes below 38 and 72 goes below 40. What goes below element 39 is different in different tables. Some place 57 below 39, and have 58-71 off separately in the lanthanide block. Some place 71 below 39 and have 57-70 in the lanthanide block. Some just have a general reference to the lanthanides below element 39, and have 57-71 in the lanthanide block.

The same applies to the Actinides as well: some consider them to be 89-102, some 89-103, and some 90-103. The one thing that is uniform across periodic tables is that a given table will follow the same convention for lanthanides and actinides. If the lanthanides are 57-70, the actinides are 89-102; if the lanthanides are 57-71, the actinides are 89-103; if the lanthanides are 58-71, the actinides are 90-103.

However, Wikipedia currently isn't even consistent in this way: the Lanthanides article says they're 58-71, but the Actinides article says they're 89-102.

It's easy enough to edit Lanthanides and Actinides to reflect this lack of consensus. However, the real issue comes in which convention should be used for periodic tables on Wikipedia, as different conventions are currently used in these:

• Tables where lanthanides are elements 57-70:
  • Periodic table (standard)
  • Periodic table (alternate)
  • Periodic table (big)
  • Periodic table (huge)
  • Periodic table (detailed)
  • Periodic table (extended) (note this assignment is certainly right for this particular table because elements are assigned to groups based on their theoretical electron configuration; this is also evidenced by helium's placement above beryllium as opposed to its usual place above neon)
  • Periodic table (electron configurations)
  • Periodic table (metals and non-metals)
  • Periodic table (block)
• Table where lanthanides are elements 57-71:
  • Periodic table (wide) (by color coding)
• Table where lanthanides are elements 58-71:
  • Periodic Table

Chuck 22:58, Jun 2, 2005 (UTC)

I'd vote for 57-70 (and 89-102 for actinides) (with Lutetium under Yttrium and Lawrencium under Lutetium). All four (Sc, Y, Lu, Lr) are clearly the first transition metals (with one 3d, 4d, 5d, and 6d electron, respectively) in their row, with all previous subshells completely filled.

Now... getting really tedious: Looking through the electron configurations:

3d begins filling immediately with Scandium, with the 4s subshell sometimes temporarily losing an electron to 3d. With Zinc, all the started subshells are full and 4p is still empty. For Yttrium it's very similar, with 5p staying empty until group 13.

Lanthanum (57), starts with a 5d, not a 4f, electron. Cerium (58) adds a 4f, and then Praseodymium has 3 4f and no 5d electrons, whereafter 4f consistently fills until Ytterbium, where it's permanently filled, and all started subshells are now full, and 5d has throughout at most one electron, (and this for only three elements - La (57), Ce (58), and Gd (64) ). Seems to me that Ytterbium (70) is a very nice element to end the 4f block on. Lutetium has one 5d electron (the first "transition" element in row 6), and the 5d orbitals continue to fill consistently up to and including Hg (80) (the last row 6 "transition" element), after which 6p begins filling.

The Actinides are similar to the Lanthanides - Ac (89) has 1, Th (90) 2, Pa (91) 1, U (92) 1, Np (93) 1, and Cm (96) 1, 6d electron(s), and No (102) has all its started subshells filled, with 6d empty. Note that Lawrencium (103) (the first row 7 "transition" element) temporarily has a 7p electron before the first 6d. Cn (112) seems to be the last row 7 "transition" element. 75.82.122.28 (talk) 00:50, 9 June 2020 (UTC)

This problem mostly arises because kainosymmetric 4f orbitals have a rather weak (though present) contribution to chemistry, so that La to Lu are all fairly similar; this doesn't happen for 5f, and so individual actinoids are much more distinctly characterised. If the strong force were a little stronger and stability disappeared at the end of period 7 rather than 6 (while leaving chemical properties the same), then I think everyone would consider it obvious that the actinoids stop at No; even from the little we know now, Lr is a lot more distinct from late actinoids than Lu is from late lanthanoids. Double sharp (talk) 07:24, 29 October 2024 (UTC)

Lutetium

It never seems to make sense to include Lutetium in the series.

I disagree, I think it's a borderline case, just like lanthanum, which has no f electrons at all, and its ions are [Xe] which makes it closest to Sc or Y, and rather like Al. In my research on lanthanide triflates I found a big difference in reactivity between La(OTf)3 and the triflates Ce(OTf)3 onwards. Lutetium has a full set of f electrons, but then so does Yb metal, does that mean Yb gets ruled out too? We run into the same arguments with the d-block, are Sc and Zn really transition metals? If Zn is not, then what about Pd, a classic transition metal yet d¹⁰? I think we can make arguments back & forth, but it's all academic. I think the periodic table solution they have used is great, thanks.

Scandium and Yttrium ([Ar]4s2,3d1 and [Kr]5s2,4d1 and Lutetium and Lawrencium ([Xe]6s2,5d1,4f14 and [Rn]7s2,6d1,5f14) are similar in configuration - imho all 4 are in the d block - actually group 3. Lanthanum and Actinium ([Xe]6s2,5d1 and [Rn]7s2,6d1) also appear to be in the d block - however, here the f block is in play according to the Madelung rule - and I see them both not as group 3, but as in between groups 2 and 3, since the d electrons disappear later and the f orbitals are all filled within 14 elements, before the d orbitals begin refilling (with Lu & Lr).

Zn, Cd, Hg and Cn are all d block - I would like to call them "transition", but I'm not a chemist - this is my take thinking about the electron configurations. It seems simpler and more intuitive to arrange the table according to the Madelung rule, with the actual elements sometimes deviating from it. There's a great periodic table @ https://en.wiki.x.io/wiki/Alternative_periodic_tables#Major_alternative_structures. 75.82.122.28 (talk) 04:23, 9 June 2020 (UTC)

lanthanide vs lanthanoid

IUPAC argues that the -ide ending is reserved for a binary compound, such as chlorides, nitrides or oxides. The -oid ending means "similar to" as in humanoid or android. Therefore, I propose to use the new official name first, with the old -ide ending as a synonym. --Gunnar (talk) 11:30, 1 September 2020 (UTC)

No consensus exists to enact this change—as of now, it's just a proposal—so I have reverted it. We can repost this talk page section and the revision ID to WT:ELEM, where a discussion can be had if necessary. ComplexRational (talk) 21:14, 5 September 2020 (UTC)

ComplexRational, I assume that Wikipedia including ELEM does not do original research and therefore did only repeat the naming as determined by IUPAC, who seems to be the legitimate authority on terminology questions.

The 1985 “Red Book” (p. 45) indicates that the following collective names for groups of atoms are IUPAC-approved: actinoids or actinides, lanthanoids or lanthanides. The note that accompanied that statement explained that although actinoid means “like actinium” and so should not include actinium, actinium has become common usage. Similarly, lanthanoid. The ending “-ide” normally indicates a negatives ion, and therefore “lanthanoid” and “actinoid” are preferred to “lanthanide” and “actinide.” However, owing to wide current use, “lanthanide” and “actinide” are still allowed. http://publications.iupac.org/ci/2004/2601/2_holden.html

Both lanthanoid and lanthanide can be used, but the preferred name is lanthanoid, whereas lanthanide is still allowed but certainly outdated and due to the reasons given on the path to be considered as obsolete in the future. --Gunnar (talk) 22:16, 5 September 2020 (UTC)

​​​​ No original research, but as far as I can tell, lanthanide and actinide are still in common use among many reliable sources (both journal articles and other tertiary reference materials) and not obsolete, so it is not a trivial matter to enact such a massive change. ComplexRational (talk) 17:35, 6 September 2020 (UTC)

Obviously the series of elements are called "lathanoids" (new name since the 80s), whereas "lanthanides" is the old name, still allowed by IUPAC but not preferred. I am wondering why you doubt this fact?

Lanthanoid, also called lanthanide, any of the series of 15 consecutive chemical elements in the periodic table from lanthanum to lutetium (atomic numbers 57–71). https://www.britannica.com/science/lanthanoid

This is from Encyclopædia Britannica, they also have discovered that the primary name ends with -oid, and the secondary ("also") with -ide. -- Gunnar (talk) 22:40, 5 September 2020 (UTC)

I'm not opposed to a change if a broad assessment of the sources would reveal that lanthanoid and actinoid are preferred. I have not yet done a more thorough investigation myself. ComplexRational (talk) 17:35, 6 September 2020 (UTC)

ComplexRational, the scientific authority about how to name elements and chemical compounds is the International Union of Pure and Applied Chemistry. The so called Red Book is the reference how to name inorganic chemicals. The last edition of 2005 shows the Periodic Table of the Elements on the page before the title page (pdf-page 2) and clearly spells out "lanthanoids". Page 336, footnote d) says: "The ending ‘ide’ in ‘actinide’ and ‘lanthanide’ indicates a negative ion. Therefore, ‘actinoid’ should be used as the collective name for the elements Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, and ‘lanthanoid’ as a collective name for the elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu (cf. Section IR-3.5)." Furthermore, Section IR-3.5 (Elements in the Periodic Table) says on p. 51 :"The following collective names for like elements are IUPAC-approved: alkali metals (Li, Na, K, Rb, Cs, Fr), alkaline earth metals (Be, Mg, Ca, Sr, Ba, Ra), pnictogens (N, P, As, Sb, Bi), chalcogens (O, S, Se, Te, Po), halogens (F, Cl, Br, I, At), noble gases (He, Ne, Ar, Kr, Xe, Rn), *lanthanoids* (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), rare earth metals (Sc, Y and the lanthanoids) and actinoids (Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr)." and on page 52: "Although lanthanoid means ‘like lanthanum’ and so should not include lanthanum, lanthanum has become included by common usage. Similarly, actinoid. The ending ‘ide’ normally indicates a negative ion, and therefore lanthanoid and actinoid are preferred to lanthanide and actinide."

The last sentence is not an observation scanning thousands of chemistry articles, it is a normative recommendation. It is obvious that in the past this group of elements was called "lanthanides". But it seems that many scientist were not very happy with this name, as '-ide' implies it is a compound like in sodium chloride or carbon monoxide, here the negative ions of chlorine and oxygen. Lanthanide is also mentioned in the Red Book on p. 311, Table IX in the column for "Anions (including anion radicals) or anionic substituent groups" which follows the -ide ending idea. Therefore if you talk about lanthanide there is some ambiguity: is it the negative ion of lanthanum or is it the whole series of lanthanum like elements?

Consequently, the IUPAC changed the naming scheme (in 1985, maybe earlier), by which they declared that lanthanoid is the new preferred way to name this group. Of course, it does not make to sense to forbid the old name, which has been in use for decades / centuries, so the old name is still allowed, but not recommended by IUPAC due to the logical weakness. It will probably take a couple of generations of new students who rise up, learn the new name and become professors and professionals themselves until in recent literature the lanthanoid spelling is dominating. Maybe it is similar to the notion that Pluto is not a regular planet any more. I have learned in my school time it is planet #9. But to sum up: the scientific research community has declared that the name of the series of elements #57-#71 is "lanthanoids", whereas it is still possible to call it "lanthanides" (not preferred = not recommended by IUPAC), due to the semantic problem the -ide ending has. While the "-oid" ending means "similar to" such as humanoid, the semantic conclusion would be that the similar to #57 elements are only #58-#71, and not #57 itself. But due to common use to have the series starting at the naming father lanthanum, this little semantic contradiction is accepted and also lanthanum itself belongs to the lanthanum like elements.

The lanthanoid /ˈlænθənɔɪd/ (IUPAC nomenclature, also called lanthanide /ˈlænθənaɪd/) series of chemical elements, ... means exactly this: official name is lanthanoid, but it is also called (not preferred by the scientific committee which is responsible for naming chemical stuff, but still in may minds) lanthanide. --Gunnar (talk) 15:38, 8 September 2020 (UTC)

My thoughts: if OP is right (esp re "-ide" and "-oid" chemical naming convention), that should solve it. However, since many sources & conventions use the current form, the name change proposal is not convincing.

enwiki should make an RFC with a wide research on sources, via WP:ELEMENTS preferably, to conclude on a RL scientific usage convention. -DePiep (talk) 20:28, 6 September 2020 (UTC)

@DePiep: What do you mean by "OP" above? It isn't clear to me. Thanks. YBG (talk) 00:39, 7 September 2020 (UTC)

"OP" = original post; opening post in top by Gunnar (IUPAC argues that ...). -DePiep (talk) 09:35, 7 September 2020 (UTC)

Wikipedia is a mess because of users like you. Instead of listening to reason and logic, you revert good edits for no good reason other than bureaucratical inertia. "-oid" suffix means something entirely different than "-id", and just because there are errors in dictionaries doesn't mean they should be perpetuated. The name is lanthanoid and actinoid. "Lanthanum alike" and "actinium alike". Lanthanids and actinids would be ionic compounds with lanthanum and actinium acting as anions. Lajoswinkler (talk) 21:13, 27 August 2024 (UTC)

This discussion should probably occur at WT:ELEM. YBG (talk) 00:39, 7 September 2020 (UTC)

It already is, see Wikipedia_talk:WikiProject_Elements#Lanthanoid_vs_Lanthanide where a general question has been asked. Chemistry geeks may know: when was actually the switch from -ide to -oid? This was at least already done in 1985, see Holden article, but may be earlier. This here is the relevant article which deals with lanthanide / lanthanoid elements and needs proper implementation. --Gunnar (talk) 14:19, 8 September 2020 (UTC)

This is not the first time this has been discussed. Despite being IUPAC convention, "-oid" has not been widely adopted in the literature compared to "-ide". Here is an old discussion where there was consensus to keep the -ide naming convention. Polyamorph (talk) 15:10, 8 September 2020 (UTC)

Per WP:OFFICIALNAMES it does not really matter what the official name is, wikipedia article titles should use the WP:COMMONNAME. This is established consensus and does not really require further discussion, especially since this lathnan-ide/oide naming convention has been discussed several times before. Polyamorph (talk) 16:23, 8 September 2020 (UTC)

The IUPAC reasoning convinced me, because the purpose is to reduce ambiguity. I am not sure if "lanthanide" in the sense of a negative lanthanum ion actually exist, but nevertheless "lanthanide" does not fit into the whole "-ide" family. And I don't agree that it is a question of a common name, because the commoner would not find lanthanum nor the lanthanoids on a map. Both are names for professionals, one is rather old and therefore still rooted firmly in many brains, and the newer one is more precise, but slowly growing in use (maybe because many semi-specialists don't know and their textbooks don't tell). In 2011 the Britannica moved from lanthanide to lanthanoid, see https://www.britannica.com/science/lanthanoid and press the info button. --Gunnar (talk) 21:21, 8 September 2020 (UTC)

From WP:OFFICIALNAMES Wikipedia:Article titles is the relevant policy and reads in part: Article titles should be recognizable to readers, unambiguous, and consistent with usage in reliable English-language sources. In many cases, the official name will be the best choice to fit these criteria. However, in many other cases, it will not be. The article title policy later reads Wikipedia does not necessarily use the subject's "official" name as an article title (emphasis added). On wikipedia we go by what the sources say, not what the "official" terminology is. Polyamorph (talk) 13:41, 9 September 2020 (UTC)

And what do sources say about the term "lanthanide"?? Do they say that many people still prefer this term over lanthanoid even if they understand the reason lanthanoid has become official?? Georgia guy (talk) 13:46, 9 September 2020 (UTC)

That would be useful if you wanted to include some information in the article on the terminology. WP:Article titles is wikipedia policy for which there should be no argument. The common usage of the term in the scientific literature is clearly with the suffix -ide: For a crude metric check the 20,000 google scholar hits for lanthanoid (10%) cf. 170,000 for lanthanide (90%). Pointless re-hashing this discussion over and over. Polyamorph (talk) 14:49, 9 September 2020 (UTC)

I interpret the lines you quoted in green as a guideline. First, there is the principle: If you know the rule, you are able to break it (or translated: No rule without exception. If arguments can be agreed on, then there is always the option for a derogation). The sentence: "The article title policy later reads Wikipedia does not *necessarily* use the subject's "official" name as an article title." explains that there is not automatism if there is an official name. This is a door opener, but it does not forbid to use the official name.

Without doubt [1], "lanthanides" are still more often written down than "lanthanoids". Nevertheless, this does not mean that the most often used term is automatically the article title, eg. Kalashnikov rifle. Both AK47 and Kalashnikov (without rifle) are much more often used in literature [2]. --Gunnar (talk) 18:55, 9 September 2020 (UTC)

It is not a guideline, WP:OFFICIALNAMES is an explanatory supplement of WP:Article titles which is WP:POLICY. Yes there is room for special cases, but this is not the general wikipedia practice. You'll need to get support to overturn the current documented consensus already cited. Polyamorph (talk) 19:08, 9 September 2020 (UTC)

I had to learn that: "It's a Wiki", so basically everbody can do whatever hesheit wants, but others follow that rule as well. As guidelines can be changed without the consent of the parliament, they are not really binding. And to be even more picky: the words "not necessarily" emphasise that the very general rule is to use the official name, but this is not hard coded. If there are good reasons, also the commonly used name can be used, e.g. AK47 instead of Kalashnikov assault rifle. Therefore - as everywhere in Wikipedia - the guidelines give a direction, but if there are good reasons you may deviate from anything (as I said, we are not in a legally binding contract which may help us to sue each other). In principle, I reject the argument "this is forbidden by principle" and ask for a technical discussion. --Gunnar (talk) 14:41, 10 September 2020 (UTC)

No, just because it is a wiki does not mean anyone can do as they like. Anyone can edit but there are still rules. Policy and guidelines built on consensus. There is already an established consensus against implementing the name change to -oid. To override this you will need to find a new consensus. Polyamorph (talk) 14:52, 10 September 2020 (UTC)