Talk:Electron configurations of the elements

Reference by Haire

This newly added reference seems to be the only source for the undiscovered elements, Z > 118. Could we please have more information on what it contains. Perhaps a sentence such as This article contains predicted electron configurations for the elements 119-168, based on approximate relativistic Hartree-Fock-Dirac calculations with configuration interaction and spin-orbit coupling by X and Y (journal reference). Note that my version is probably incorrect because I have not seen the article and I am guessing, but it illustrates the level of detail which I believe should be added to the mention of Haire's article. Dirac66 (talk) 15:04, 3 December 2012 (UTC)

 Done Double sharp (talk) 06:10, 4 December 2012 (UTC)

Don't worry, i will go and do some research things. Hubbiety (talk) 09:16, 22 December 2016 (UTC)

Chromium and other exceptions

To Bobdolan22 and everyone else who keeps trying to "correct" chromium: The point is that the Madelung rule (1s, 2s, 2p, 3s, 3p, 4s, 3d, etc.) is only an approximation, and there are lots of exceptions of which chromium is the first. Yes, the rule would say that Cr is 4s²3d⁴, but the experimental atomic spectrum shows that it is actually 4s¹3d⁵. This article gives the true experimental configurations, even when they disagree with the Madelung rule. For more discussion see Electron configuration#Aufbau principle and Madelung rule. Dirac66 (talk) 01:06, 25 March 2013 (UTC)

Perhaps interesting cases and exceptions to important "rules", like that which you mentioned, can be pointed out on the article in some way? JonathanHopeThisIsUnique (talk) 04:07, 7 January 2016 (UTC)

Good idea. I have now added a second short paragraph in the introduction to the table, to explain what the rule is and to point out that there are numerous exceptions. Dirac66 (talk) 18:11, 7 January 2016 (UTC)

I should also point out that these "irregularities" are an artifact of insisting on ground-state gas-phase electron configurations. The d and f elements have lots of configurations very close in energy and difference in chemical environments can easily change which happens to be the ground state, so the Madelung exceptions you often see actually have very little relevance to real chemistry. In particular, the Madelung-predicted configurations like [Ar]3d⁴4s² are always at least close to the ground state for the first 118 elements, well within the range of chemical bond energies. The ref and paragraph I added points out this chemical irrelevance of the irregularities. Double sharp (talk) 07:59, 28 May 2020 (UTC)

New property for WikiData

Please vote for new property of WikiData - "Electron_configuration" creation Васин Юрий (talk) 18:32, 22 August 2019 (UTC)

Nefedov

Hi - comparing and contrasting this with Periodic Table I see Nefedov et al's results are not examined here - http://www.primefan.ru/stuff/chem/nefedov.pdf. They are quite different – FLYING CHRYSALIS ^💬 20:37, 27 December 2019 (UTC)

There have not been complete and conclusive results from E123 onwards: there are many disagreements in the sources (the two Fricke papers do not even agree with each other 100% IIRC). I suppose we should mark this as just one possibility, and present the others as well, and do the same Extended periodic table. That would be more in line of what the other data pages do, e.g. Boiling points of the elements (data page). Double sharp (talk) 04:58, 28 December 2019 (UTC)

I definitely support that; we'd then have to add additional rows for each undiscovered element and label them as distinct predictions from different sources (or some other substantial reformatting). ComplexRational (talk) 13:22, 28 December 2019 (UTC)

Perhaps there should be several tables, labelled something like "Configurations determined from experimental spectra", "Configurations predicted for known elements" and "Configurations predicted for undiscovered elements." Dirac66 (talk) 21:46, 28 December 2019 (UTC)

Sure, that would be all right. @ComplexRational: What's the last element for which the configuration is actually determined from experimental spectra? AFAIK that for Lr is only inferred from volatility experiments, for example, not directly measured. Double sharp (talk) 06:38, 29 December 2019 (UTC)

@Double sharp: According to the articles and ref Silva, it seems the last directly confirmed configuration is Fm. ComplexRational (talk) 14:26, 29 December 2019 (UTC)

@ComplexRational: OK, so I guess we would have to split into H through Fm (determined from spectra); Md through Hs (inferred through chemical experiments); Mt through Og (calculations only); E119 and up (calculations only, elements not even discovered). Double sharp (talk) 15:21, 29 December 2019 (UTC)

Yes, and we can add notes to the element entries to deal with special cases, as for Nickel in the table now.

Also note that there is some information on the reliability of the result for each element in the References section, especially in the WebElements subsection. But the table should still be divided up to make the point more clearly. Dirac66 (talk) 01:55, 30 December 2019 (UTC)

The g shell configurations should be regarded as tentative, and I'm not sure that it even makes sense to assign a single configuration. In my (unpublished) DHF/CI calculations on single configurations 5g^j 6f^k 7d^l 8s^m 8pⁿ, there are often near-degeneracies, e.g. 6f³ 8p¹ and 6f² 8p², and even indeterminate 5g occupations around Z=129-131. So these are very multi-reference states with many possible contributing configurations. KGDyall (talk) 20:46, 11 September 2020 (UTC)

@KGDyall: Hey, thanks for telling us this! I've added a brief note about the tentativeness beyond E120 to the article, citing the Nefedov article above.

You might like to talk to Droog Andrey too: he's also a computational chemist (I'm not), and he has some great ideas about how post-120 elements should best fit into the periodic table. Double sharp (talk) 13:19, 12 September 2020 (UTC)

Dirac66 I've been discussing this with ComplexRational on his talk page, and looking around at various sources, and it looks to me like we should really prune this table because there is not much agreement between sources past 121 in fact. (Nefedov in fact makes something close to the point KGDyall did above; there is so much configuration interaction that a single configuration may well start becoming a little bit nonsensical.) Therefore I am thinking that this table should be pruned to either element 118 (predictions up there) as the heaviest known element, or element 121 (three more predictions) as the heaviest element for which all contemporary sources seem to agree on the configuration; and to leave what lies ahead to Extended periodic table (where the table should be edited to show all the possibilities that have been floated, I guess). What do you think? Double sharp (talk) 13:37, 11 February 2021 (UTC)

Thanks for telling me about the article Extended periodic table of which I was not aware. The last section Extended periodic table#Electron configurations seems to be a good presentation of the predictions for the undiscovered elements, so I don't think it is necessary to repeat the information in this article. Therefore I now think that this article should end with Oganesson (E118), at least until more elements are actually discovered. This can be followed by a link explaining that predicted configurations for undiscovered elements to E173 are in the other article.

And I still think it would be a good idea to indicate the type of data for each element Z = 1-118. We could divide the table into three parts as discussed above (H-Fm, Md-Hs, Mt-Og), but this division could become awkward if in the future the elements in each category are no longer consecutive. Suppose for example that in 2025, someone reports chemical experiments which indicate the configuration of Flerovium (E114) only. Do we then put it in Table 2 even though Mt-Nh are still in Table 3 (calculations only)? A more flexible presentation allowing for new data might be to retain one table, but to add after the name of each applicable element words such as "based on chemical behavior" (for Md-Hs now) and "predicted from theoretical calculations" (for Mt-Og now). Dirac66 (talk) 21:22, 11 February 2021 (UTC)

One table sounds the best to me for those reasons. So, we'll revert to when this stopped at Og, and add new elements as predictions only when they're discovered. Double sharp (talk) 07:16, 12 February 2021 (UTC)

P.S. It does not seem like the sources are making much of the distinction between configurations from direct measurement and configurations from inferences – see for example NIST which just gives everything till Hs without comment. So, I have stuck with the lede statement that elements beyond Hs are just predicted and a two-way division between experimentally known and experimentally unknown. Double sharp (talk) 10:09, 12 February 2021 (UTC)

I think that it is much better now. I have added a See also link to the extended table Z = 119-173 so the information will be accessible. However by putting it in a separate article it seems clearer that the configurations are not to be taken as seriously for undiscovered elements. Dirac66 (talk) 16:36, 12 February 2021 (UTC)

Electron configurations of monovalent ions

Data from https://www.nist.gov/pml/atomic-reference-data-electronic-structure-calculations/atomic-reference-data-electronic-8. Data for elements beyond U are predictions.

The elements having irregular electron configurations for their atoms also have irregular electron configurations for monovalent ions. V, Co, Ni, Y, Lu have regular electron configurations for their atoms but their monovalent ions are irregular.

The elements having only one (n-1)d electron (Y, Lu, Ac, Pa, U, Np, Cm) tend to lose its (n-1)d electron before ns when forming monovalent ions. This does not apply to Sc and Gd, which lose an ns electron before (n-1)d. La and Ce even lose two ns electrons and get one more (n-1)d electron. Here Lu (and not La) behaves as the real homologue of Y.

Z	Symbol	Electron configuration by Aufbau principle	Actual electron configuration	Note
1	H	-
2	He	1s1
3	Li	1s2
4	Be	[He] 2s1
5	B	[He] 2s2
6	C	[He] 2s2 2p1
7	N	[He] 2s2 2p2
8	O	[He] 2s2 2p3
9	F	[He] 2s2 2p4
10	Ne	[He] 2s2 2p5
11	Na	[He] 2s2 2p6
12	Mg	[Ne] 3s1
13	Al	[Ne] 3s2
14	Si	[Ne] 3s2 3p1
15	P	[Ne] 3s2 3p2
16	S	[Ne] 3s2 3p3
17	Cl	[Ne] 3s2 3p4
18	Ar	[Ne] 3s2 3p5
19	K	[Ne] 3s2 3p6
20	Ca	[Ar] 4s1
21	Sc	[Ar] 3d1 4s1
22	Ti	[Ar] 3d2 4s1
23	V	[Ar] 3d3 4s1	[Ar] 3d4	Has one more 3d electron than unionized atom
24	Cr	[Ar] 3d4 4s1	[Ar] 3d5
25	Mn	[Ar] 3d5 4s1
26	Fe	[Ar] 3d6 4s1
27	Co	[Ar] 3d7 4s1	[Ar] 3d8	Has one more 3d electron than unionized atom
28	Ni	[Ar] 3d8 4s1	[Ar] 3d9	Has one more 3d electron than unionized atom
29	Cu	[Ar] 3d9 4s1	[Ar] 3d10
30	Zn	[Ar] 3d10 4s1
31	Ga	[Ar] 3d10 4s2
32	Ge	[Ar] 3d10 4s2 4p1
33	As	[Ar] 3d10 4s2 4p2
34	Se	[Ar] 3d10 4s2 4p3
35	Br	[Ar] 3d10 4s2 4p4
36	Kr	[Ar] 3d10 4s2 4p5
37	Rb	[Ar] 3d10 4s2 4p6
38	Sr	[Kr] 5s1
39	Y	[Kr] 4d1 5s1	[Kr] 5s2	Losing 4d electron before 5s
40	Zr	[Kr] 4d2 5s1
41	Nb	[Kr] 4d3 5s1	[Kr] 4d4
42	Mo	[Kr] 4d4 5s1	[Kr] 4d5
43	Tc	[Kr] 4d5 5s1
44	Ru	[Kr] 4d6 5s1	[Kr] 4d7
45	Rh	[Kr] 4d7 5s1	[Kr] 4d8
46	Pd	[Kr] 4d8 5s1	[Kr] 4d9
47	Ag	[Kr] 4d9 5s1	[Kr] 4d10
48	Cd	[Kr] 4d10 5s1
49	In	[Kr] 4d10 5s2
50	Sn	[Kr] 4d10 5s2 5p1
51	Sb	[Kr] 4d10 5s2 5p2
52	Te	[Kr] 4d10 5s2 5p3
53	I	[Kr] 4d10 5s2 5p4
54	Xe	[Kr] 4d10 5s2 5p5
55	Cs	[Kr] 4d10 5s2 5p6
56	Ba	[Xe] 6s1
57	La	[Xe] 4f1 6s1	[Xe] 5d2	Has one more 5d electron than unionized atom
58	Ce	[Xe] 4f2 6s1	[Xe] 4f1 5d2	Has one more 5d electron than unionized atom
59	Pr	[Xe] 4f3 6s1
60	Nd	[Xe] 4f4 6s1
61	Pm	[Xe] 4f5 6s1
62	Sm	[Xe] 4f6 6s1
63	Eu	[Xe] 4f7 6s1
64	Gd	[Xe] 4f8 6s1	[Xe] 4f7 5d1 6s1
65	Tb	[Xe] 4f9 6s1
66	Dy	[Xe] 4f10 6s1
67	Ho	[Xe] 4f11 6s1
68	Er	[Xe] 4f12 6s1
69	Tm	[Xe] 4f13 6s1
70	Yb	[Xe] 4f14 6s1
71	Lu	[Xe] 4f14 5d1 6s1	[Xe] 4f14 6s2	Losing 5d electron before 6s
72	Hf	[Xe] 4f14 5d2 6s1	[Xe] 4f14 5d1 6s2	Losing 5d electron before 6s
73	Ta	[Xe] 4f14 5d3 6s1
74	W	[Xe] 4f14 5d4 6s1
75	Re	[Xe] 4f14 5d5 6s1
76	Os	[Xe] 4f14 5d6 6s1
77	Ir	[Xe] 4f14 5d7 6s1
78	Pt	[Xe] 4f14 5d8 6s1	[Xe] 4f14 5d9
79	Au	[Xe] 4f14 5d9 6s1	[Xe] 4f14 5d10
80	Hg	[Xe] 4f14 5d10 6s1
81	Tl	[Xe] 4f14 5d10 6s2
82	Pb	[Xe] 4f14 5d10 6s2 6p1
83	Bi	[Xe] 4f14 5d10 6s2 6p2
84	Po	[Xe] 4f14 5d10 6s2 6p3
85	At	[Xe] 4f14 5d10 6s2 6p4
86	Rn	[Xe] 4f14 5d10 6s2 6p5
87	Fr	[Xe] 4f14 5d10 6s2 6p6
88	Ra	[Rn] 7s1
89	Ac	[Rn] 5f1 7s1	[Rn] 7s2	Losing 6d electron before 7s
90	Th	[Rn] 5f2 7s1	[Rn] 6d1 7s2
91	Pa	[Rn] 5f3 7s1	[Rn] 5f2 7s2	Losing 6d electron before 7s
92	U	[Rn] 5f4 7s1	[Rn] 5f3 7s2	Losing 6d electron before 7s
93	Np	[Rn] 5f5 7s1	[Rn] 5f4 6d1 7s1
94	Pu	[Rn] 5f6 7s1
95	Am	[Rn] 5f7 7s1
96	Cm	[Rn] 5f8 7s1	[Rn] 5f7 7s2	Losing 6d electron before 7s
97	Bk	[Rn] 5f9 7s1
98	Cf	[Rn] 5f10 7s1
99	Es	[Rn] 5f11 7s1
100	Fm	[Rn] 5f12 7s1
101	Md	[Rn] 5f13 7s1
102	No	[Rn] 5f14 7s1
103	Lr	[Rn] 5f14 6d1 7s1	[Rn] 5f14 7s2
104	Rf	[Rn] 5f14 6d2 7s1	[Rn] 5f14 6d1 7s2
105	Db	[Rn] 5f14 6d3 7s1	[Rn] 5f14 6d2 7s2
106	Sg	[Rn] 5f14 6d4 7s1	[Rn] 5f14 6d3 7s2
107	Bh	[Rn] 5f14 6d5 7s1	[Rn] 5f14 6d4 7s2
108	Hs	[Rn] 5f14 6d6 7s1	[Rn] 5f14 6d5 7s2
109	Mt	[Rn] 5f14 6d7 7s1	[Rn] 5f14 6d6 7s2
110	Ds	[Rn] 5f14 6d8 7s1	[Rn] 5f14 6d7 7s2
111	Rg	[Rn] 5f14 6d9 7s1	[Rn] 5f14 6d8 7s2
112	Cn	[Rn] 5f14 6d10 7s1	[Rn] 5f14 6d9 7s2
113	Nh	[Rn] 5f14 6d10 7s2
114	Fl	[Rn] 5f14 6d10 7s2 7p1
115	Mc	[Rn] 5f14 6d10 7s2 7p2
116	Lv	[Rn] 5f14 6d10 7s2 7p3
117	Ts	[Rn] 5f14 6d10 7s2 7p4
118	Og	[Rn] 5f14 6d10 7s2 7p5
119	Uue	[Rn] 5f14 6d10 7s2 7p6

129.104.241.193 (talk) 20:58, 24 April 2024 (UTC)

I made some changes to your table, per NIST (up to Hs) and the calculations in doi:10.1007/1-4020-3598-5_14 (Mt-Cn). Double sharp (talk) 10:39, 3 May 2024 (UTC)

P.S. for divalent ions (once the g-shells come in, these will probably be close to the ground state in many cases, though I won't be surprised if they're not exactly the ground state). Double sharp (talk) 10:42, 3 May 2024 (UTC)

Thanks! 129.104.241.193 (talk) 21:09, 5 May 2024 (UTC)

Thanks to the link you provided, I could list the exceptions for divalent ions as follows:

Z	Symbol	Electron configuration by Aufbau principle	Actual electron configuration
57	La	[Xe] 4f1	[Xe] 5d1
64	Gd	[Xe] 4f8	[Xe] 4f7 5d1
71	Lu	[Xe] 4f14 5d1	[Xe] 4f14 6s1
89	Ac	[Rn] 5f1	[Rn] 7s1
90	Th	[Rn] 5f2	[Rn] 5f1 6d1
91	Pa	[Rn] 5f3	[Rn] 5f2 6d1
103	Lr	[Rn] 5f14 6d1	[Rn] 5f14 7s1
104	Rf	[Rn] 5f14 6d2	[Rn] 5f14 7s2
105	Db	[Rn] 5f14 6d3	[Rn] 5f14 6d2 7s1
106	Sg	[Rn] 5f14 6d4	[Rn] 5f14 6d3 7s1
107	Bh	[Rn] 5f14 6d5	[Rn] 5f14 6d4 7s1
108	Hs	[Rn] 5f14 6d6	[Rn] 5f14 6d5 7s1
109	Mt	[Rn] 5f14 6d7	[Rn] 5f14 6d6 7s1
110	Ds	[Rn] 5f14 6d8	[Rn] 5f14 6d7 7s1
111	Rg	[Rn] 5f14 6d9	[Rn] 5f14 6d8 7s1
112	Cn	[Rn] 5f14 6d10	[Rn] 5f14 6d8 7s2

It is quite irregular that Y²⁺, Ce²⁺, Hf²⁺, U²⁺, Np²⁺, and Cm²⁺ are regular. It is even more astonishing that Th³⁺ might be regular (5f¹). 129.104.241.193 (talk) 21:22, 5 May 2024 (UTC)

Some time ago I wrote a note (h) in Periodic table about this kind of thing. There's a gradual transition between the Madelung order (roughly correct at zero charge) and simply filling in order of n (roughly correct for almost-bare nuclei). Within the chemically relevant ionisations for metals (roughly +2 to +6), this amounts to a mild correction to Madelung for the most part, in which (n−1)d and (n−2)f get drowned below ns and np. The 6d metals are exceptions for relativistic reasons. Double sharp (talk) 08:48, 6 May 2024 (UTC)