Commons:Featured picture candidates/File:NaCl polyhedra.svg

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Voting period is over. Please don't add any new votes.Voting period ends on 30 Aug 2021 at 18:13:40 (UTC)
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Crystal structure NaCl polyhedra

For its usage please look at this page, Special:GlobalUsage/NaCl_polyhedra.svg

  •  Info Charlesjsharp, Daniel Case,Colin I can't see anywhere that FP must have "Academic authentication", does that go for all images of plants, animals etc? To me this starts to fell like it's out of focus for what is FP or not. There is no why I can provide that info as I'm a graphic worker without knowledge of all most everything I do here. How shall I solve that? --always ping me-- Goran tek-en (talk) 14:24, 23 August 2021 (UTC)[reply]
  • Of course the images should have Educational Value but this is the first time I had to prove this in some way and has never heard about it. My believe was that this was a "self regulation" place just as wikipedia, if something is wrong someone will tell you.
I have posted questions in different places to get some answers here and I hope someone will attend to the questions. --always ping me-- Goran tek-en (talk) 17:25, 23 August 2021 (UTC)[reply]
But DePiep also say "We do not have "authentication" at wiki ;-)" regarding "Academic authentication" which is what I tried to say before. I hope his extensive information gives you all the information you need. --always ping me-- Goran tek-en (talk) 19:51, 23 August 2021 (UTC)[reply]


  • (ec) re "academic authentication" (read as en:wp:RS etc.).
(1) As for the regular, alternating, cubic stacking: correct for NaCl, and is a statement that is unlikely to be challenged (see en:Wikipedia:Verifiability). IOW, it is commonly accepted to be true & correct for NaCl, and so does not need specific RS-sourcing.
(2) as for the two "cubic-like" items: this is a visualisation, not physically present. It illustrates the surrounding (positioning) of a grey atom by six Na-atoms, on a en:triangular bipyramid (six corners = atoms); en:octahedron. It is described here: "It is obvious from the diagram that each chloride ion is surrounded by six sodium ions which are disposed towards the corners of a regular octahedron". BTW, the source supports the (1) cubic stacking claim.
re "which atomes are what": The smaller, gray ones are Na en:sodium, the larger green ones are Cl en:chlorine. The difference in size is according to their physical atomic (ionic) size.
However, I have advised the autohor to use more standard atom coloring. Generally, PyMol colors are encountered as conventional (elements colors en:Wikipedia:WikiProject Chemicals/Elements coloring scheme). So in here:
Na rgb(161,086,229) #A156E5 a purple; (now grey) see right values below 13:17, 24 August 2021 (UTC)
Cl rgb(029,191,029) #1DBF1D a green; (now green)
The ball-shading-effect best be kept, to support the 3D effect.
As for "educational value": IMO, the stacking, in combination with the colors, shows the crystal structure full stop. Then, the octahedrons very nicely add the crystal effect of a Cl atom being positioned beteen six Na atoms: nice illustration of this crystal property. (I might add, rare to see crystal properties illustratied & clarified this well).
-DePiep (talk) 20:36, 23 August 2021 (UTC)[reply]
Correct PyMOL colors, from source PyMOL:
Na #aa5cf2 ([0-1] scale: 0.670588235, 0.360784314, 0.949019608), sodium  Na 
Cl #1ef01e ([0-1] scale: 0.121568627, 0.941176471, 0.121568627), chlorine  Cl 
Goran tek-en -DePiep (talk) 13:17, 24 August 2021 (UTC)[reply]
  •  Support I remember this kind of illustration from the geology lectures I attended ages ago. Many of them were either butt-ugly or difficult to wrap your head around. This one is neither, it manages to illustrate this aspect of the 3D structure of NaCl exceptionally well by clever use of shading and transparency. This is a textbook level illustration that is useful far beyond just NaCl, as several other salts have this same crystalline structure (de.wikipedia even has an article about that: Natriumchlorid-Struktur). BUT: even though it is not reqired by the license of File:NaCl polyhedra.png, it feels very wrong to me that User:Solid State was credited as the original author in the appropriate field of the file description page. Give credit where credit is due. I've fixed that for you, please keep it in mind for the future. --El Grafo (talk) 07:29, 24 August 2021 (UTC)[reply]
  • Authors go in the authors= field. All of them. Sorry, can't support a file for FP that does not give proper credit. --El Grafo (talk) 06:42, 25 August 2021 (UTC)[reply]
  •  Info El Grafo I'm following the traditions here at commons and I even put more info than required. He is the author of the source not this SVG image, two completely different things. You can't set up your own rules for what is right or wrong, you have to follow what is agreed to here at commons. To me your behavior is "selfish". --always ping me-- Goran tek-en (talk) 14:18, 29 August 2021 (UTC)[reply]
  •  Oppose Goran tek-en The problem with this representation is that it is misleading in an important way. The sodium en:cation and the chloride en:anion appear here not to be in contact with one another: the lines of the grid look as if they are meant to represent en:chemical bonds. In reality, the structure is held together by en:electrostatic interactions (the positively charged sodium attracts the negatively charged chlorine). In standard chemical representations, this should be shown with the spheres representing the ions touching at their en:Van der Waals radius, specifically in this case the en:ionic radius (that's the article that explains the issue best). If you compare the illustration in the Chembox of the en:sodium chloride article, you'll see why I think the current image is misleading, if not wholly wrong since it does show the atomic centres correctly. Hence I don't think it should be a featured image. Michael D. Turnbull (talk) 11:16, 24 August 2021 (UTC)[reply]
  •  Info It's very hard for me as a graphic worker when people say "this is wrong/this is correct" as I have zero knowledge of the subject. It would be great if you chemistry people discussed this and if it's possible to reach an agreement do so. If you in consensus think this image should look differently please just ping me and assist me to create an illustration that is correct. If there are different opinions I'm more than willing to create different versions. --always ping me-- Goran tek-en (talk) 14:17, 24 August 2021 (UTC)[reply]
  • As I noted earlier, I'm no chemist, but I'm a bit sceptical about Michael D. Turnbull's comments. As mentioned above, the model is similar in many ways to that at Chemtube3d (especialy after clicking on "Coordination"). It is also similar to File:NaCl-Ionengitter.svg and others at Category:Crystal structure of sodium chloride. What we have here is a Ball-and-stick model whereas Michael appears to want a Space-filling model. It isn't for Commons to decide which model is best or should appear on Wikipedia, as long as the model here is valid and similar to those in reliable sources. I suggest if this remains unclear, that a request is made to Wikipedia:WikiProject Chemicals for more opinions. -- Colin (talk) 14:41, 24 August 2021 (UTC)[reply]
  • I am impressed by the User:Michael D. Turnbull reply (whose wiki contribitions I know to be thoroughly well seasoned, chemically speaking). Nice to note: their reply does not concern the crystallography, but the chemical bonding representation. Some honour is saved ;-) That is: size of balls, and the drawing of sticks between them (here in colors green-white) is the problem. So, given (=accepting from MDT) that the bonding is different, image File:Sodium-chloride-3D-ionic.png says something different.
This scientific detailing must lead to the conclusion that the image is not correct enough for FP.
Now how to turn this image into a correct one, per MDT? Obviously, remove the between-atomic-balls sticks (no such bonding). Also, change ball size (keeping anion/cation relative sizes) to make them touching & give stable ball stacking. However, then both illustrative en:octahedrons would become invisible? These are the main assests of currewnt image! A puzzle for the graphist to solve.
-DePiep (talk) 20:36, 24 August 2021 (UTC)[reply]
  • DePiep To my understanding this illustration is a Ball-and-stick model representation and not a Space-filling model which you suggest it should be turned into. The Ball-and-stick model does not depict how something is actually looking rather a way to visualize what is happening in a more easy way to view it. The Space-filling model is on the other hand more of a representation of how it really looks. This is two completely different things and should not be mixed, line drawing vis-a-vis oil panting.
If you are interested of a Space-filling model I would be more than will to work with you on it, just pung me. --always ping me-- Goran tek-en (talk) 09:43, 25 August 2021 (UTC)[reply]
re: I was re-describing what Michael D. Turnbull wrote. For example, MDT: "the lines of the grid look as if they are meant to represent en:chemical bonds [but ...]". Also, the en:Ball-and-stick model you linked to says: "... to display both the three-dimensional position of the atoms and the bonds between them" (while, as MDT writes, there are no bonds but there are just electrostatic interactions) -DePiep (talk) 11:02, 25 August 2021 (UTC)[reply]
Thanks, DePiep for backing up my comments. I think I can express the issue in another way that may help. There are two general bond types in chemistry, ionic and covalent. When we think of a compound "AB" we can write A+B- as a good way of expressing the ionic option. Or we could write A–B to show the covalent option. Some compounds have both type of bond (e.g. A–B–C+D-). What is the key difference in behaviour? Well, for one thing, ionic compounds completely lose their integrity on dissolving them in water or melting them. That means that if we recrystallise them or re-freeze them, the individual ions don't revert to the positions they previously held: they randomize. Whereas, when a covalent compound like acetic acid = CH3COOH dissolves in water the methyl group never becomes detached from the carbonyl group: when re-isolated they are still covalently bonded, although other molecules of the acid do freeze independently. And sodium acetate displays both behaviours: the methyl group stays attached to the carbonyl group BUT the sodium atom is promiscuous: it moves around in solution independently. Hence the "best" simple drawing is CH3COO–Na+. Incidentally, the atoms in covalently-bonded compounds frequently end up closer together than the sum of their ionic radii. They share molecular orbitals in a way that ionic compounds (of which sodium chloride is a classic example) can't. So the challenge for Goran tek-en in trying to create a really superior image is to use some cunning transparency in the lattice made up of filled atoms to add the polyhedron whose role is to illustrate the closest neighbours of a given single atom (a chloride in the current drawing on the right and a sodium on the left). I have no objections to using lines within these polyhedra, to represent their edges, not bonds. The result will some sort of combination of the polyhedra with a drawing like File:NaCl.png. Michael D. Turnbull (talk) 12:12, 25 August 2021 (UTC)[reply]
  •  Info Michael D. Turnbull, DePiep Thanks both of you for a lot of info although I not really get it all. To be able to go further and to be able to create an even better image I will start a thread on my talk page and I invite you both to help me in creating that image. I will have questions and sometimes you will have to explain in a more layman way for me, I will ping you and ask you to join. --always ping me-- Goran tek-en (talk) 13:20, 25 August 2021 (UTC)[reply]
Confirmed results:
Result: 2 support, 1 oppose, 1 neutral → not featured. /--MZaplotnik(talk) 21:03, 30 August 2021 (UTC)[reply]
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