Talk:Atomic radius

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Radius vs atomic number Plot Needed[edit]

This article really needs an image showing a plot of atomic radius versus atomic number, something like this. While the raw numbers and colors on the period table are nice, it is hard to get a feel for the detailed quantitative trends using such a presentation alone. Has this been discussed and consensus reached against it in the past? — Preceding unsigned comment added by (talk) 15:14, 6 October 2011 (UTC)

Metal radius is "another name for atomic radius"?[edit]

Can somebody check to make sure this article is correct in saying metalic and covalent radii are other names for certain types of atomic radii?

I think at least 'covalent radius' is described correctly (in the way my teacher has used it, and he should know - he used to be a professor). Is this what you mean? sodium
This problem has hopefully been fixed by now. --Jorge Stolfi (talk) 18:43, 9 August 2009 (UTC)

this is george washingtion and i saw that this is incrediably true —Preceding unsigned comment added by (talk) 20:26, 17 April 2010 (UTC)

How can Mo be smaller than Ca?[edit]

How could the Mo be smaller in radius than Ca & more electronegative although it has 20 more electrons than Ca?

the atomic radius is also related to shielding

la risa es sana —Preceding unsigned comment added by (talk) 20:28, 17 April 2010 (UTC)

Atomic radius or electronegativity?[edit]

I realize there is a strong correlation between atomic radius and electronegativity, but might it be better to have the chart list the atomic radii?

I agree. It is misleading to title the page & section "Radius" while listing electronegativities in the periodic table. BeefGood 12:40, 29 March 2007 (UTC)
I also agree -- it took me quite a while to work out what the first table is. How about we move the electronegativity table to the bottom, and label it more clearly? atakdoug 05:22, 13 April 2007 (UTC)
Hopefully this problem has been fixed, and the tables now show atomic radii (even if the "wrong" type of radii). If the numbers are still electronegativities, the tables must be removed immediately! All the best, --Jorge Stolfi (talk) 18:43, 9 August 2009 (UTC)

A note of appreciation[edit]

To all the wonderful editors who have added to this article, thank you! It's been a great help. This article was created in 2002 and back then it looked pretty bad. Now it's a fine article indeed. Thanks! Goyston talk, contribs, play 15:00, 15 June 2007 (UTC)

Saint Petersburg[edit]

Besides being a silly way to say that two things are far apart, the sentence about Saint Petersburg(s) is technically incorrect. Even ignoring the fact that an electron anywhere near these two places would become entangled in the matter surrounding it, there is a finite distance that an electron can travel from a nucleus before the atom is considered ionized. In calculating the stable states for any atom, the wavefunction becomes zero with increasing distance, it does not asymptotically approach zero. It is OK to say that the border of the atomic radius is "fuzzy" since the actual point where the wavefunction becomes zero will likely be somewhere past the distance accepted as the common atomic radius.

This complaint seems to be moot by now. --Jorge Stolfi (talk) 18:37, 9 August 2009 (UTC)


I believe the following reference:

E. Clementi, D.L.Raimondi, and W.P. Reinhardt, J. Chem. Phys. 1967, 47, 1300.

is actually:

Clementi, E. (1967). "Atomic Screening Constants from SCF Functions. II. Atoms with 37 to 86 Electrons". Journal of Chemical Physics. 47: 1300–1307.  Unknown parameter |coauthors= ignored (|author= suggested) (help)

So it only appears to cover a subset of the periodic table. There was also a reference:

Clementi, E. (1963). "Atomic Screening Constants from SCF Functions.". Journal of Chemical Physics. 38: 2686–2689.  Unknown parameter |coauthors= ignored (|author= suggested) (help)

that may cover elements 2-36 (but I don't have access to check.) Even with that, however, the page is still missing references for elements 88-217.—RJH (talk) 21:01, 28 January 2008 (UTC)

bond lengths/van der Waals radii[edit]

The values given in this chart look suspiciously like bond lengths to me. Personally I would think that van der Waals radii would be more accurate. Em3ryguy (talk) 03:44, 3 June 2008 (UTC)

Agreed, for other reasons too. See "Slater reference" section below. --Jorge Stolfi (talk) 18:36, 9 August 2009 (UTC)

Slater reference[edit]

In the section "Empirically measured atomic radius", the reference given (J.C. Slater, J. Chem. Phys. 1964, 41, 3199.) does not quote any values for noble gases -- Where have these numbers come from? (talk) 05:05, 23 June 2009 (UTC)

Indeed. I have temporarily removed the noble gas entries, and note that the other values are covalent radii (hope so). The table should be changed to show van der Waals radii, since the noble gas column is very important for the next section. All the best, --Jorge Stolfi (talk) 18:34, 9 August 2009 (UTC)

atomic radius vs atomic volume[edit]

If I take a mole of some element, measure its volume, then divide by 6.024 * 10^23, and then find the radius of the sphere with that volume, what am I measuring? Van der waals radius? just-emery (talk) 00:13, 4 July 2009 (UTC)

You'll probably be better pressed asking on the reference desk. --Izno (talk) 00:50, 4 July 2009 (UTC)

What determines atomic radius?[edit]

I think that the statement The atomic radius is determined entirely by the electrons in the third paragraph is misleading because it may give the impression that atomic radius is unaffected by or unrelated to the composition of the nucleus. Is there a better way to put this? Myceteae (talk) 06:23, 31 July 2009 (UTC)

The lead has been rewritten and hopefully that problem has been fixed. --Jorge Stolfi (talk) 18:30, 9 August 2009 (UTC)


-- (talk) 11:56, 2 September 2009 (UTC)

Why are atomic radii as large as they are?[edit]

Why are atomic radii as large as they are? Why are atomic radii so much larger than the nucleus? Why does matter have volume? Investigating the parallel question of "Why does matter have mass" lead to the discovery of the Higgs particle. Is there a similarly vigorous inquiry into why does matter have volume? Thanks! --Lbeaumont (talk) 15:08, 26 November 2014 (UTC)

Radius of hydrogen calculated from hydrogen density[edit]

Density of solid hydrogen = 0.086 g/cm^3

A hydrogen molecule has a mass of approximately 2 neutrons therefore a volume of 4*10^7 pm^3

2 neutron mass/(0.086 g/cm^3) in pm^3 = 4*10^7 pm^3 = (340 pm)^3

340 pm is much larger than the diameter given in the article

Just granpa (talk) 06:18, 6 December 2016 (UTC)

Density of liquid helium = 0.125 g/cm^3

A helium atom has a mass of approximately 4 neutrons therefore a volume of 5.36*10^7 pm^3

4 neutron mass/(0.125 g/cm^3) in pm^3 = 5.36*10^7 pm^3 = (374 pm)^3

374 pm is much larger than the diameter given in the article

Just granpa (talk) 06:41, 6 December 2016 (UTC)