Talk:Effective nuclear charge

References and Citing

This article only has two references, and they are to articles by the same author. Does this represent some bias in the information presented? In addition, there are no citations in text, just links to other articles on Wikipedia. Does this mean that the information presented is reliable and fact-based or is it more opinion based?

Chemgirl13 (talk) 03:06, 1 September 2016 (UTC)

Confusion between Effective Nuclear Charge and Nuclear Attraction

The article asserts that effective nuclear charge decreases down a group in the periodic table. This is used to rationalise the fact that ionisation energies decrease down a group. Effective nuclear charge does not in fact decrease down the group: if anything, it increases.

Effective nuclear charge modifies the actual nuclear charge for the effects of electron shielding (as stated in the article). However, it does not take into account the distance of the electron in question from the nucleus. Using Slater's Rules, referred to in the article, the effective nuclear charges of hydrogen, lithium and sodium are 1, 1.3 and 2.2 respectively. The reason the ionisation (British sp.) energy decreases is that the outer electron is further from the nucleus and therefore experiences less nuclear attraction (Coulomb's law). CSM 11:41, 11 August 2006 (UTC)

Simplistic

My understanding was that the interpretation that shielding was caused by the inner orbital electrons was a low level anaology to tell to people unfamiliar with quantum mechanics, and that the shielding effect was actually caused by the quantum foam and its associated particle pair production/annihilation causing the vacuum to behave as a non-linear dielecteric which meaning that the electric fields of the various constiuents of the atom do not decay as according to coulomb's law. —Preceding unsigned comment added by 129.67.39.207 (talk) 23:35, 10 June 2010 (UTC)

Well, if you have no inner electrons, you have no shielding, so it is hardly a "low-level" analogy to say that shielding is caused by the inner electrons. It is more complicated that the simple model of fixed shells of electrons would imply, but that doesn't mean you need to go into high-level quantum electrodynamics to explain the chemical effect. Physchim62 (talk) 11:52, 16 September 2010 (UTC)

Zhang Effective Nuclear Charge

A Spectroscopic Quantum Model 1. Effective Nuclear Charge 2. Effective Principal Quantum Number

Yonghe Zhang

FullText(SpQtmModel)

Abstracts：Based on the Bohr quantum energy levels, a spectroscopic quantum model for easily calculating the effective nuclear charge Z* and the effective principal quantum number n* from the ionization energy Iz of the all orbitals from 1s to nf is established:

Z*=n*(Iz /R)½

No longer using the traditional rules for estimating artificially the shielding effects, the modelsuccessfully derived many important quantitative methods，such as the IC-model, electronegativity, Lewis acid strengths, crosslink density and effective Polarizing Power, which can calculate and describe quantitatively chemical phenomena and the dual observations of the ionic and the covalent of bond, correlated with chemical theorems and regulations andpredicted chemical processes and products.

Fenhmm (talk) 19:01, 12 May 2013 (UTC)

Article cites incorrect data

this article concludes "... the radius of the sodium cation is smaller than that of Neon". This statement is not true. See the page http://en.wikipedia.org/wiki/Fajans%27_rules for a summary of the data. The radius of the sodium cation is larger than that of Neon. The same data which is presented on Fajan's rules is replicated (and I believe both are correct) on the page of ionic radius http://en.wikipedia.org/wiki/Ionic_radius In summary, this article needs to be completely rewritten.

65.219.197.117 (talk) 13:14, 5 December 2014 (UTC)Dr. Mack

proposal for adding method of approximately calculating effective nuclear charge

I found this site has a method to calculate effective nuclear charge by calculating shielding constant which can be very helpful than seeing this site for values again and again; also you don't have to remember those values. I don't know how scientifically true this method is but can be helpful

it states as follows:- Slater's Rules

The electronic structure of the atom is written in groupings as follows: (1s), (2s, 2p), (3s, 3p), (3d), (4s, 4p), (4d), (4f), (5s, 5p), (5d), (5f)... Electrons in higher groups than the electron you are considering (to the right on the list) do not shield electrons in lower groups. For ns or np electrons: Electrons in the same ns, np group contribute 0.35, except when considering electrons in the 1s orbital, where 0.30 works better. Electrons in the n-1 group(s) contribute 0.85. Electrons in the n-2 or lower groups contribute 1.00. For nd and nf valence electrons: Electrons in the same nd or nf group contribute 0.35. Electrons in groups to the left contribute 1.00.

EXAMPLE

Bromine (1s)2 (2s, 2p)8 (3s, 3p)8 (3d)10 (4s, 4p)7

Then write out an equation for the screening constant according to the appropriate Rule - 3 or 4.

Here, Rule 3 applies. There are 6 other electrons in the same ns, np group. There are 18 electrons in the n-1 groups. (3s, 3p and 3d) There are 10 electrons in the n-2 and lower groups. (1s, 2s and 2p) σ = 6(0.35)+18(0.85)+10(1.00) σ= 27.

--Anish59312 (talk) 05:18, 13 October 2020 (UTC)

References

Data in table are different from cited source

The table of values cites Clementi et al. for Z < 37. I checked that source (full text available at Sci-Hub, but Wikipedia won't allow me to link to it here) and it appears that most of the data there do not agree with the table in the Wiki article. For example:

• Lithium

- Table in Wiki article: 1s 2.691,  2s 1.279
- Table in Clementi:     1s 2.6906, 2s 0.6396

• Potassium

- Table in Wiki article: 1s 18.490,  2s 13.006, 2p 15.027, 3s 8.680,  3p 7.726,  4s 3.495
- Table in Clementi:     1s 18.4895, 2s 6.5031, 2p 7.5136, 3s 2.8933, 3p 2.5752, 4s 0.8738

The values agree with Clementi for 1s, but are different for all other orbitals.

I suppose one of three things needs to happen:

• Something is added to explain the discrepancy, or
• The table is changed to agree with the cited data, or
• The table is deleted as being unsupported by the cited references.

Ennex2 (talk) 16:18, 15 October 2024 (UTC)

A friend that I sent this to pointed out the rather simple relationship in the discrepancy, which is:

• (Value in Wiki table) = (Value in Clementi) * n

where n is the principle quantum number.

Clementi's table gives values of the orbital exponent xi, which he says satisfies the relation:

• xi = (Z - s) / n

where Z is the atomic number, s is the screening (or shielding) constant, and n is A FUNCTION OF the principle quantum number.

If Zeff = Z - s, then

• Zeff = xi n

If n here were the principle quantum number, then this would satisfactorily explain the discrepancy between the table in the Wiki article and in Clementi. But n here is not the principle quantum number, but is a function of the principle quantum number. Clementi specifically does not state the relationship between xi in his table and Zeff, but cites other references for that relationship. in particular, he does not say, nor imply, nor even hint, that Zeff = xi * (principle quantum number).

It therefore seems to me that the table of values is wrong and should be removed from the article. However, I am not sufficiently knowledgeable in this field to take it upon myself to remove the table.

I note that this Talk page has complaints above about problems in this article that go all way back to 2006, almost 20 years ago. I don't see any indication of whether these complaints have been addressed and either the article corrected based on them or the complaints found to be invalid. This is deeply disturbing. It suggests the possibility that this article has been presenting incorrect information about effective nuclear charge for almost 20 years, that various people have been pointing out flaws in the information, and that the information has not been corrected. This article may be a glaring example of how dangerous it can be to believe what one reads in Wikipedia.

Ennex2 (talk) 05:36, 16 October 2024 (UTC)