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It seems that on the page exactly the same text exists. How is this possible?

The above question was asked years ago, but I'll respond anyway. mirrors all content of Wikipedia. There was no plagiarism involved; simply copied the article. The GFDL allows, and encourages, such copying. - Pingveno 19:34, 29 July 2006 (UTC)

Question about a specific pair of molecules (title added)[edit]

I have a question: Is SiF4 and SiCl4 isoelectronic species? —The preceding unsigned comment was added by (talkcontribs) .

According to the definition given here, they are, because they have the same structure and the same number of valence electrons. I vaguely remember reading something that used a stricter definition which required the whole electron configurations to be the same, but I can't remember what it was. I probably just imagined it. =P —Keenan Pepper 04:48, 3 September 2006 (UTC)
No, you didn't imagine it. Ne, HF, H2O, NH3, and CH4 are all isoelectronic molecules. The definition which uses valence electons instead is a generalization of the former. Page 94 of Chemical Structure and Bonding by R.L. DeKock and H.B. Gray state this. --HappyCamper 00:30, 21 November 2006 (UTC)
Now that I read this article, this needs a fixup... --HappyCamper 00:31, 21 November 2006 (UTC)

- No two elements are isoelectronic. They can only be isoelectronic if they have added an electron (negative charge) or lost an electron (positive charge). This is how Argon can be isoelectronic to Sulfur: S + 2 electrons = Ar, S^(-2) = S + 2 electrons; therefore, Ar is isoelectronic to S, if Sulfur has a negative 2 charge.


Why would it be signioficant that two molecules are isoelectric? I was seeing notes in a couple of articles that they are isoelectric to carbon dioxide and my real reaction is: so? RJFJR 14:19, 8 March 2007 (UTC)


"the amino acids cysteine and serine are also considered isoelectronic"

don't think so at all - S is not isolectronic to O, at all. Is this a biological usage that differs? (talk) 12:58, 2 September 2009 (UTC)

With the addition valence the statement stands in respect with respect to the given definitions of (valence) isoelectronicity.T.vanschaik (talk) 11:53, 19 September 2009 (UTC)

Clarifying the lede[edit]

I've just made an edit, dropping the term "molecular entity" from the lede - "chemical species" is more familiar .. and hopefully, in the context, sufficiently equivalent!

Later in the article the term "species" is used - with, in the context, the same meaning; and the change of terminology is distracting. (At best it requires a mental adjustment by the reader; at worst it draws the reader to click into IUPAC terminology swamps.)

The alternative was to level the terminology the other way (ie using "molecular entity" throughout rather than using "chemical species"). I'm not sure there's much to choose in terms of theoretical accuracy / precision. The Gold Book uses "molecular entity", but "chemical species" is more readily abbreviated (for fluency; to "species"), in the running copy, and "molecular entity" is so rarely used that in a lede it functions as a minor distraction in itself. (talk) 17:22, 21 December 2016 (UTC) (talk) 18:28, 21 December 2016 (UTC)

I'm also changing the order of the differing definitions! The Gold Book is clear, current and authoritative, and defines isoelectronicity in terms of valence electrons. (It simply omits core electrons from consideration.) It's possible to define it more tightly (or at least has been possible in the past). And the Advances Vol.30 reference considers more-inclusive ("relaxed") possibilities. But I can't see us doing anyone any favors by starting out in conflict with IUPAC. Alternative definitions need to come later in the lede.

Also - regarding authority, credibility etc - I'm dropping the free dictionary as a reference (as it gives no sources and is doubtless not compiled by chemists). (talk) 05:10, 22 December 2016 (UTC)