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)

IUPAC convention for Periodic Table

IUPAC proposed a Periodic Table

http://www.iupac.org/reports/periodic_table/index.html

why not using this convention?

I changed the article (and actinide-article) to use IUPAC convention and to make it consistent with Wikipedia peridic table. --Levil 02:04, 23 August 2005 (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.

Lanthanide compounds

I am the perverse character who wrote fairly lengthy articles on things like praseodymium(III) chloride, but I wanted to seek people's opinions on other compounds. I wrote a set of articles on most LnCl3 from Ce to Dy, and I still plan to do a couple of other chlorides, as well as some oxides such as Tb4O7. For major compounds like oxides & chlorides this seems worthwhile. However it would seem to be a big waste of time to write a separate page on each one of the 14 sulfates, each of the 14 nitrates, etc. I was thinking of writing a general page on lanthanide sulfates, one on lanthanide nitrates, etc. What do people think of this idea? What should such pages be called? And yes, I would include both La and Lu! Walkerma 16:35, 8 September 2005 (UTC)

IUPAC recommendation

Why not move this page to Lanthanoid and redirect Lanthanide there instead?

I second that and suggest that Lanthanon also be redirected to Lanthanoid. Squideshi 04:08, 26 August 2007 (UTC)

what are lanthanides in

what are you talking about?! --feline1 11:26, 17 January 2006 (UTC)

This may relate to the group number. See discussion here, this explains why we omit the group no. from the individual element pages, though I note that Group 3 element does still include them. Basically, IUPAC hasn't made a decision on this, until they do it's up in the air. Walkerma 15:26, 17 January 2006 (UTC)

well so what? what actual difference does it make to anything? it's just arbitrary nomenclature! Their chemical behaviour won't change no matter what "group" IUPAC decides to put them in!--feline1 15:46, 17 January 2006 (UTC)

Actually definitions do matter, 10 minutes ago I just happened to re-read a patent of mine, where it refers to the patent covering metals from group 3. We explicitly mentioned lanthanides, but if we hadn't, there could be a lawsuit over it! More generally, students may get homework questions like, "List all of the group 3 elements." Also, there is a space on every element page to indicate the group number, this is noticably absent now for lanthanides and actinides - it seems reasonable for someone to ask why. Walkerma 19:34, 17 January 2006 (UTC)

well lawyers will find ways to swindle you whatever nomenclature you use /yawns/ "Groups" are just conveniences of classification: nature and chemistry don't become more easy to understand just because the narrow-minded try and box it into inappropriate nomenclature schemes.--feline1 22:03, 17 January 2006 (UTC)

Nature and chemistry become incomprehensible without classification into scientific models. An encyclopedia cannot explain anything without defining its nomenclature. Narrow-minded is who does not arrange their knowledge. Femto 12:51, 18 January 2006 (UTC)

Look, Mendeleev decided to collect elements into groups because of similarities in their chemical behaviour. A "group" is not a "scientific model" (it does not seek to explain anything), it is just a handy bit of taxonomy. Some of the elements don't exhibit very strong group behaviour in the vertical direction and so it's seldom very useful talking about them like that... for other groups (eg alkali metals), it *is* very useful. Elements do not *have* to be "in a group"... the properties of the 14 lanthanoids are primarily down to their f electrons and so it is useful to think of them as a group (small g) on their own... it is not particularly useful to talk about them being in any of the 18 vertical Groups (big G) because none of those have f electrons - however, as we all know, Group 3 are their nearest cousins. You are all talking as if Groups are some sort of innate part of nature which elements have to "belong" to - but they're not, they're just a human idea to help keep things tidy, and some elements don't fit into them very well. Get over it!--feline1 14:24, 18 January 2006 (UTC)

I'd like to add, if this is an encyclopedia it should be accurate to the chemical world and what chemists use. We've had the same discussions in transition metal. Yes it does matter! You should not just put stuff in Wikipedia because you think your notiont is OK--it does matter to many of us. Olin

[…] --feline1 23:12, 6 February 2006 (UTC) -- Personal attack removed. Wikipedia:No personal attacks. Femto 16:58, 9 February 2006 (UTC)

You are not an encyclopedic resource. If you can't use those qualifications to provide references showing that your point of view is neutral, derogative remarks won't convince anyone either. Femto 16:58, 9 February 2006 (UTC)

Mnemonics

Do we really need a mnemonic device in the article, it doesn't really seem to have anything to do with the actual information of lanthanides. And IMO, its not that good of a mnemoic to begin with.--24.180.19.26 16:38, 10 January 2007 (UTC)

Mnemonics are common pedagogic devices used when teaching chemistry - by all means find a better one if that one is a bit rubbish.--feline1 18:01, 10 January 2007 (UTC)