Talk:Electronegativity

Previously the article said that a large electronegativity difference results in ionic bonding, 0.2 - 1 polar, and below 0.2 non-polar. My chemistry book says >=2.0 forms an ionic bond, 0.4 - 2.0 polar covalent, and <=0.4 nonpolar covalent. Note that I'm using the Pauling scale. The electronegativity scale was not specified, so I changed the values.

Jeff Connelly 01:10 28 May 2003 (UTC)

I thought that ionic was over 1.7. -Smack 01:56 9 Jul 2003 (UTC)

Actually, EN difference alone does not, strictly, determine the ionic/covalent nature, for example, solid LiH, delta EN = 1.1, is ionic, whereas SiF₄, delta EN = 2.1, is covalent!

Furthermore, the whole scale is a continuum. It's not like when you go from 1.9 to 2.1 all of a sudden the bonds have completely changed. Olin 14:31, 3 March 2006 (UTC)

Someone should say something about the elements that do not have electronegativities (i.e. the actinides and noble gases). -Smack 01:56 9 Jul 2003 (UTC)

The article says Francium has the least electronegativity then it says Caesium does. I know electronegativities increase across periods and decrease down groups but I want to know what the exceptions are and why this article has contradicted itself?

In theory, francium would be the least electronegative. However, due to all its isotopes' extreme radioactivity and rapid decay, it could never be feasibly experimented with or observed. For this reason, caesium is usually referred to as the "least" or "most" (e.g., most reactive in group I, least electronegative, etc.) in cases where francium deserves that title. Maybe this should be mentioned in the article?

Doshea3 10:17, 29 May 2005 (UTC)

Could someone add a word about chemical potential?

I would love to see a few words relating electronegativity to the chemical potential.

plagiarism somewhere

See http://encyclopedia.laborlawtalk.com/Pauling_scale - this seems to be word-for-word the same as the Wiki article. Who copied from whom? Cbdorsett 10:58, 23 Mar 2005 (UTC)

- An entry has been added to the linked above website noting the source as Wikipedia.

They are a mirror of us. — Omegatron 15:10, 6 December 2005 (UTC)

Definition

I removed:

Electronegativity is a measure of the attraction that an atom has for the bonding pair of electrons in a covalent bond.

Replaced with:

Electronegativity is the ability of an atom or a molecule to attract shared electrons to itself.

This latter is a far more general, certainly more accurate definition. Electronegativity is a trait considered not only in covalent compounds, but in Ionic and polar covalent as well.

So I see someone reverted my edit without even a discussion? The current definition is even more incorrect than it was...reverting edit of "195.194.86.166"

• I'm afraid I am confused as to the definition of this word. Surely, although related, the ability of an atom to attract electrons and form anions is quantitively different to the attraction an atom may have to attract electrons in an already existing covalent bond? Obviously there is a strong positive correlation between the two, but they seem quite distinct to me. --postglock

Origin of the Pauling Scale?

Does anyone know how the intermediate values of the Pauling scale were assigned? The current article sidesteps the issue. On the first read through, I got the impression the values were assigned relative to Fluorine & Francium, but on careful review, this doesn't seem to be the case. (At anyrate, it ignores how each atom was interpolated, anyway.) 23:02, 8 Jun 2005 (UTC)

Addendum: The body of the article says Fluorine is assigned as 4.0, but the table gives a value of 3.98 - 23:07, 8 Jun 2005 (UTC)

If X_a is the elektronegativity of element a en X_b that of element b then X_a-X_b=sqrt(delta/23) with D(AB)=sqrt(D(A_2)*D(B_2))+delta and D(...) the dissociation energy of the molecule.. That's how i learned it..

Accuracy Disputed Tag

I've added an accuracy disputed tag, because the initial definition is not precise and probably incorrect. It seems to me that the energy involved in creating anions is probably the incorrect meaning here, and the correct meaning is to do with the attraction in existing covalent bonds. The energy involved in creating a -1 ion appears to be called electron_affinity, and so I would assume that this is a distinct and separate meaning. If anyone could clear this up, it would be appreciated. -- postglock 4 July 2005 08:45 (UTC)

Maybe I can help clear this up. Simply put, Electronegativity is the ability of an atom to attract electrons. Period. An atom's ability to attract electrons is not affected by any bonds that it is in. Rather, both atoms are pulling with their respective Electronegativities, and the type of bond formed is the result of this tug-of-war. I think the opening of this article should read "Electronegativity is the measure of the ability of an atom or molecule to attract electrons. The type of bond formed is determined by the difference in Electronegativity between the two atoms. Atoms with similar Electronegativities will constantly 'steal' an electron from each other (commonly referred to as 'sharing') and form a covalent bond. However, if the difference is too great, the electron will be permanently transferred to one atom and an ionic bond will form. Furthermore, if one atom pulls slightly harder than the other, a polar covalent bond will form." Now here's where the different scales come in. Also, the specific values for each kind of bond should be removed from the trends section and put in their respective scale sections. That information has nothing to do with periodic trends. Also, the rounded figures need to go, and the whole Mulliken scale needs some serious help. Given the stamp of approval, I'd be glad to do all these things.the1physicist 9 July 2005 04:37 (UTC)

I hereby give you my stamp of approval, as an official Chemistry and Physics teacher. I think that's as official as it gets on the Wikipedia, right? RobertAustin 00:52, 19 October 2006 (UTC)

I think I may be partly confused about the differences concerning bonds. I have read that chemical bonds range from ionic to polar covalent to non-polar covalent, but I've never totally understood this. Obviously the degree of polarity may be a continuous range, but surely there are distinct differences between covalent and ionic bonds per se? (i.e. by simply counting whether electrons are shared or borrowed to fill shells) Regardless, surely in terms of the different scales, these have been empirically produced from some consistent procedure? (e.g. change in energy when adding an electron? or level of polarity in covalent bonds?)

In any case, if you feel that you can improve this article, you should be bold in updating pages! Go for it!

--postglock 07:28, 13 July 2005 (UTC)

The degree of polarity is indeed a continuous range. There are not really 'distinct' differences between closely separated bonds types. (That is, a 1.4 bond behaves similarly to a 1.5, etc.) In terms of an exact numerical cutoff for each bond type, that doesn't really exist. You will find slightly different numbers in different books. I noticed 67.134.186.74 updated the article with an interesting example, so allow me to point out his error. True, the bond between Si and F *should* be ionic, but that same Silicon atom is being shared with 4 Fluorine atoms. Because of this, the pull of the Silicon atom is essentially reduced by a factor of 4, and hence, it is covalent. I could go into much further detail, but it would be much too complicated and this is not the place. More importantly, I think it confuses things more than it adds clarity, so I would be in favor of removing it. I guess I'll make some edits and see what happens.the1physicist 21:56, 13 July 2005 (UTC)

The reason I had added the LiH / SiF₄ examples is to demonstrate something. You see, whether a compound is ionic or covalent is determined not by electronegativity difference, but rather by whether the lattice energy is enough to compensate for the energy required for ion formation. Solid LiH is an ionic compound because the energy required to form Li⁺ and H^- ions is compensated for by the lattice energy of combination of such ions. On the contrary, the formation of Si⁴⁺ and F^- ions is unfavorable because the charge density of Si⁴⁺ would be extremely high. Therefore, SiF₄ is covalent, even though its E.N. difference is nearly twice that of ionic LiH. My whole point, I shall repeat, is that whether a compound is ionic or covalent is determined not by electronegativity difference, but rather by whether the lattice energy is enough to compensate for the energy required for ion formation. I feel that it's too much of a misconception.

You basically have to ask yourself what is lattice energy? And the (overly) simplified answer is that lattice energy is just a nice number that lets us do equations easier. The important thing to remember here is that lattice energy is determined by the forces between the atoms and electrons. Hence, we're talking about one and the same thing, so I see no need to obfuscate the matter (pun intended).the1physicist 04:19, 15 July 2005 (UTC)

For those who like it simple, DO NOT READ BEYOND THIS POINT! The whole concept that each element can be assigned a single value that defines how it attracts electrons is by far an over-simplification. Even the same two elements can form different types of compounds. MnO is an ionic compound, but Mn₂O₇ is covalent! It just isn't right to say that the electron-drawing ability of an atom of a particular element is a constant. It depends on the circumstances. It is simply wrong that atoms of a particular element always have the same potential to draw bonding electrons toward themselves!

I believe it may be time to move this sub-discussion to another page.

Diamond is electronegative?

The article here says that diamond is highly electronegative. Could someone confirm and then add it to the article? It would be useful to go into why diamond being electronegative would be a useful property. --ShaunMacPherson 02:08, 13 September 2005 (UTC)

It wets steel... It's sabotaged by H². It really wants to bond with something else, if you know what I mean. Diamonds aren't forever. ;D lysdexia 04:08, 6 November 2005 (UTC)

[C-C bonds are pretty strong compared with many other group 14's. The article is "popular" science, it is not the most brilliant description, basically it refers to nano-tubes of diamond, and mentions an electronegative surface - but this still brings you back to treating the surface C you want to bond something to as just a generic carbon. I would argue that this article is probably pretty "specialist", and that for this article is not very relevant in itself.]

Anthropomorphism

Atoms with similar electronegativities will constantly 'steal' an electron from each other (often misleadingly referred to as 'sharing')

Uh... how is that more misleading than saying they "steal"? — Omegatron 15:09, 6 December 2005 (UTC)

[Technically they do share electron density - there is no more appropriate simple word. They "require" electrons and thus "share" them, to steal electrons does suggest more of an active conscious mode of going about this, when in reality the electron orbitals will be distorted by localised charge interactions. In some way you could say steal, but only if you subscribe to primitive methods of viewing electrons, as it would suggest you could at any one time say that one of the pair of atoms in a diatomic "owned" the electron at that moment, before the other atom takes it. This is impossible thanks to that nice man with his uncertainty principle. Thus even in models of "full" ionic systems modeled using DFT techniques etc. even though the ionic nature is explicitly shown you have to say that there are regions of electron denisty that are effectively zero.]

Stealing/sharing?

What do u mean by 'Atoms with similar electronegativities will constantly 'steal' an electron from each other (often misleadingly referred to as 'sharing') and form a covalent bond.' Isn't it called as sharing?

I believe that was a typo. Unless I'm mistaken, it should read "and form an ionic bond." Then again, I failed Chemistry my fourth term..

Electrolysis

a simple electrolysis example needs to be included. not only is this the place people often come across electronegativity, a neat example would also give a lot of people a clear picture of what this article is on about

Effective Nuclear Charge

This article would benefit from a discussion of effective nuclear charge and how it determines electronegativity. I'm no chemist, so I hesitate to write it myself. Expert needed.JohnJohn 01:40, 29 August 2006 (UTC)

Uh...??

I must say, this article is very confusing for people who don't know what covalency and all that stuff is. I thought Electronegativity was how well something conducted electricity. Caesium is supposed to be a really good insulator, right?Madking 14:29, 3 March 2007 (UTC)

Those terms used in the article here, such as "covalent bond", are wiki-linked so you can learn exactly what they mean. Caesium, being a metal, would be expected to be a good conductor. DMacks 08:40, 5 March 2007 (UTC)

Electronegativity vs Quantum Mechanics (& Critiscisms)

--4.159.77.158 22:33, 10 March 2007 (UTC) Electronegativity is an approximatation. The concept has only limited value and should not be enshrined as part of the fundamental theory of chemistry. It is useful and therefore should be learned, but, like valence, is not to be taken too literally. It breaks down if you look at it too closely.

[Agreed - I was just thinking that this was missing from discussion & article. This concept is a mathematical model only, of the complex reality - demonstrated in one of the first posts which states that a sigma of >1.7 for M-X doesn't necessarily indicate ionic bonding. As with many chemical concepts it is retained as it provides a good model to work from in most scenarios, but as such remains inherently limited. Realistically this should be mentioned, and some sort of Critiscisms section should note this and preferably reference an appropriate source - I saw something the other day that may be appropriate, dealing with organolithiums.] {Found this: "Whereas nucleophilicity and basicity are the absolutely dominant features of organic derivatives of potassium, cesium and barium, the reactions of lithium, magnesium, and zinc compounds are, in increasing order, triggered by the electrophilicity (Lewis acidity) of the metal" AND "[Organometallics where historically envisioned as M = cation, C = carbanion] ...This primitive description was very helpful when, in the years after the Second World War, G. Wittig and other pioneers began to advertise the rapidly developing branch of organometallic chemistry. Nevertheless the conceptual reduction of real organometallic species [And also, but generally to a lesser degree, the often talked about ionic M-X species] to fictional carbanions is an oversimplification which must lead to misjudgements. In fact, no difference in organometallic reactivity patterns can be rationalized unless the metal and its specific interactions with the accompanying carbon backbone, the surrounding solvent, and the substrate of the reaction, are explicitly taken into account." [Anything in square brackets I added, normal brackets are author's.] Page 9, page 10 respectively of "Organometallics in Synthesis; A Manual" Second edition, Editor: Schlosser (And this is his section), Wiley 2002, ISBN: 0 471 98416 7.