Talk:Van der Waals force

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Contents 1 Link with noble gases 2 Forces 3 Slight mixup in references 4 Achtung! 5 London forces named for Fritz London? 6 Merger 7 Possessive apostrophe 8 London force only a sub part of VDW 9 Shouldn't "oval" be "ellipsoid"? 10 Dipole moment of ellipsoid 11 Hamaker Force Interactions 12 Van der Waals' forces and Intermolecular force 13 Adhesives 14 VAn der walls forces in rubber 15 Nomenclature 16 Fraught with Errors 17 Needs an intro section 18 London forces weaker than permanent dipole-dipole interactions? 19 Make up your mind about capitalization of Van when it appears in the middle of the sentence.

[edit] Link with noble gases

I think it is the lack of strong van der waals forces that keep noble gases from condensation. It is true that these forces are present within in all molecules and even in those of the noble gas atoms. However, it is a fact that the bigger the radius of the noble gas atom (more electrons), the higher the boiling point is. This is caused by increased possibilities for temporary dipole formation. So, it strengthens the argument that it is the lack of van der waals forces that makes the noble gases so stable!

If anyone agrees with me, this has to be corrected.

I agree tho i believe more people should accept before changes are made

chemaddict 10:18, 4 June 2006 (UTC)

[edit] Forces

I think that dispersion forces should be under the title of London forces and that Van der Waals force(s) should be a redirect to intermolecular forces. Van der waals forces are called such because they account for the force part of the van der Waals equation (the forces that cause the gas to deviate from ideal behavior). I don't know if the non-London intermolecular forces account for considerable deviation from the ideal when dealing with most gases, but I don't think this is justification for restricting van der Waals to induced dipoles only. The original definition is still the correct one, and to assign both London and van der Waals to dispersion forces is redundant and confusing. Some textbooks get this right and some get it wrong, and that puts everyone on a different page. For what it's worth, the OED makes a point to specify that VdW forces are those caused by dipoles that are "actual or induced". Mauvila 05:21, 9 Dec 2004 (UTC)

I agree. As I understand it, Intermolecular Force = Van der Waals + intermolecular covalent + intermolecular ionic (with the later two being rare) and Van der Waals = London (induced dipole-induced dipole) force + dipole-dipole force + dipole-induced dipole. Therefore there should not be any redirects as Intermolecular includes Van der Waals which includes London forces, but none of them are equivalent. User:TomCounsell

Is anyone familiar with how the forces became known as VdW forces? I am assuming it it because of the VdW equation, that these are the forces responsible for deviation. Is there such thing as VdW volume? (From the other term in the equation.) Anyway, this stuff might be worth mentioning. Mauvila 21:13, 25 May 2006 (UTC)

There's a bit of controversy respect to the proper spelling of the term.See discussion here

According to Dutch spelling rules the correct title is actually Van der Waals force.

According to J.S. Dodd (Ed.), "The ACS Style Guide", ACS, Washington DC, 1986, p.28 the *recommended* spelling is "van der Waals". This style is commonly used in scientific articles.

[edit] Slight mixup in references

There seems to be slight mistake in the reference concerning the relationship between the Casimir force, the Van der Waals force, and Sonoluminesence.

• Iver Brevik, V. N. Marachevsky, Kimball A. Milton, Identity of the Van der Waals Force and the Casimir Effect and the Irrelevance of these Phenomena to Sonoluminescence,

discussing the relationship between the the three phenomena is not found at hep-th/9901011 but at hep-th/9810062.

The first link points to

• Kimball A. Milton "The Casimir Effect: Physical Manifestations of Zero Point Energy"

which has a section that discusses the relationship between the Casimir and the Van der Waals force.

cheers

tarek yousef

[edit] Achtung!

This page is duplicated(Van der Waals forces & Van der Waals force). One should be purged

[edit] London forces named for Fritz London?

Are the London forces named for Fritz London alone, or are they also named for his brother (Heinz London) who worked with him on their superconductivity theories? 194.200.237.219 13:45, 31 January 2006 (UTC)

Looking elsewhere, it seems that Fritz London worked on intermolecular forces and published something in 1930 on London dispersion forces. The London brothers work on superconductivity was later, in 1935. 194.200.237.219 15:58, 31 January 2006 (UTC)

[edit] Merger

Van der Waals bonding and Van der Waals force are basically two versions of the same article about the same phenomenon. It is unclear how they got written in parallel, but Van der Waals force seems to be both the more common name for the phenomenon and the more comprehensive (as well as referenced/sourced) article. I propose that Van der Waals bonding be merged into Van der Waals force and made a redirect. MCB 18:00, 24 May 2006 (UTC)

• Yes i agree, and most english exam bored recognise them more commonly as the Van der Waals forces so i think it is more apt to merge the two articles under one heading - Van der Waals forces. chemaddict 10:18, 4 June 2006 (UTC)
• I also agree with merger of both pages in question under one, which would be called either "Van der Waals force" or even more generally "Van der Waals interactions". The attractive force between atoms and "bonding" is virtually the same thing. For any person with interest for Van der Waals interactions, it would be more convenient to have facts from both pages combined in one comprehensive page.
• Agree - wikipedia never lets two articles on the same topic with two different titles co-exist. Merge - mastodon 18:05, 9 June 2006 (UTC)
• Agree - pointless duplication. PS - If anyone disagrees, perhaps they'd like to write an articale entitled Differences between Van der Waals force and Van der Waals bonding. --Oscar Bravo 06:57, 6 July 2006 (UTC)
  • Poorly excuted merge! I have reverted, all the editor did was delete the content of Van der Waals bonding and redirect! that is not how we do it - Jack (talk) 00:58, 21 July 2006 (UTC)
    • The guideline on merger says, "Cut/paste the non-redundant content from the source page into the destination page." However, after examining both pages, it was quite apparent that there is nothing of value in the "bonding" article that is not already covered here. If you think you can do a better job of merger, by all means feel free. But having the two redundant articles out there is not helpful to Wikipedia. --MCB 04:59, 21 July 2006 (UTC)
      • I fully agree. The text of the bonding article covered ground that is already discussed in this article, as such there is no need to make any changes. I've re-merged the article. Jrockley, if you believe there to be information missing after the merge, please add it to the current article. PureFire 09:43, 27 July 2006 (UTC)

[edit] Possessive apostrophe

As far as I know "van der Waals force" is more common than "van der Waals' force". I propose that the article text and title reflect this. — DIV (128.250.204.118 03:39, 6 March 2007 (UTC))

I see this was moved by Thomaslau on 22 November 2006 with the note, "moved Van der Waals force to Van der Waals' forces: The Correct Name". And somehow this was classed as a "minor" edit. It doesn't seem to be a minor edit, and I see no discussion. I'm quite happy with the change to plural, but not the apostrophe. — DIV (128.250.204.118 04:23, 6 March 2007 (UTC))

"Van der Waals" is singular, so to make it possessive you would typically do "Van der Waals's", even though it already ends in "s". Since no one says "Van der Waals's force", "Van der Waals force" is correct, with "Van der Waals" being a description of the type of force, not a possessive. --129.2.170.33 00:42, 14 March 2007 (UTC)

I've moved the article back. --Itub 20:57, 3 April 2007 (UTC)

[edit] London force only a sub part of VDW

"Van der Waals bonding, also known as London force, instantaneous dipole effect, and induced dipole interaction"

This is not an entirely true statement as the London interaction is only one of three (arguably there are more) intermolecular interactions in Van der Waals bonding. It is agreed in most systems that the London interactions is the only interaction to consider as the other two, Debye and Keesom, interactions sum to zero, however to totally ignore these or reference these interactions would be undermining the state of present surface and materials science.

Therefore for "Van der Waals bonding" to be a complete page I would have agree for the merger of this article and Van der Waals force, as these contributions are sighted.

Dr dagger 03:32, 13 June 2006 (UTC)

Right. Bot no one described vdW interactions as a combination of Debye (dipole-dipole), Keesome (dipole-induced dipole), and London (dispersion attraction) forces in the article. Biophys 04:35, 18 October 2007 (UTC) BTW, that is why they are "forces" (plural), not a force.Biophys 04:52, 18 October 2007 (UTC)

[edit] Shouldn't "oval" be "ellipsoid"?

The article says that the surrounding cloud forms, not a (3-dimensional) sphere, but rather a (2-dimensional) oval. I think "ellipsoid" is correct. --Carl Manaster

Yes - I fixed it. PAR 01:28, 12 October 2006 (UTC)

[edit] Dipole moment of ellipsoid

The article says: "However, the larger the atom of the noble gas, the easier it is to condense the gas. This is because a larger atom has a larger electron cloud, which more readily forms an ellipsoid, making the atom a temporary dipole."

I find this possibly confusing. The dipole moment of an ellipsoidal "electron cloud" with respect to its center is zero. I understand what is the intended meaning of the sentence I quoted, but I think it needs to be rewritten.

[edit] Hamaker Force Interactions

An moved the information from article Hamaker Force Interactions and redirected the article to Can der Waals force. I think the information below is rubbish - as googling the term find nothing except Hamaker constant, and I did not think Van der Waal's could be between two macroscopic bodies. So anyway - I have put the information below and if needed someone can put it into this article.

Hamaker Force Interactions are the Van Der Waal's forces between two macroscopic bodies. Hamaker first performed the integration of the interaction potential in 1937 using the following assumptions:

1) the total interaction can be solved by summing the pairs of force interactions.

2) the summation of assumption 1) can be approximated by integrating over the volume of the macroscopic body assuming that the volume of each atom is dV with density p

3) the material properties p and C6 (interaction constant from Van Der Waal's equation)

Cheers --Lethaniol 14:44, 25 October 2006 (UTC)

There is an orphaned article at Hamaker theory. Can someone work on this? — DIV (128.250.204.118 01:44, 23 May 2007 (UTC))

Good point. Actually important subject is Hamaker constant that has been measured for interactions between different materials in different media. We must have article about it.Biophys 04:41, 18 October 2007 (UTC)

[edit] Van der Waals' forces and Intermolecular force

Van der Waals' forces are also discussed in detail in Intermolecular force. Is there any reason why this article can not be merged into Intermolecular force. It certailny looks a mess from the point of view of doing main article links from Chemical bond. What is the view or should I add merge tags now? --Bduke 21:59, 28 November 2006 (UTC)

[edit] Adhesives

Can regular glue or tape stick to atomically smooth surfaces (or even just surfaces with no atomic overhangs)? If so, is it due to Van der Waals' forces? —Ben FrantzDale 17:02, 17 January 2007 (UTC)

See the reference about the geckos for a discussion of adhesion to smooth surfaces attributed to VdW forces. Itub 18:29, 17 January 2007 (UTC)

I saw a talk on that this morning, that's what brought me here. I am particularly curious about conventional adhesives, though, such as superglue. I think I found an answer on StraitDope.com which basically says "it could be Van der Waals' forces but the jury is still out. (It seems surprising that we would know more about gecko adhesion than about simple superglue. Science must know the answer to "does glue stick to an atomically-smooth surface".) —Ben FrantzDale 18:59, 17 January 2007 (UTC)

[edit] VAn der walls forces in rubber

I have just read an article iin a motor cycle magizine, discussing the properties of tyres, where they claim that the rubber tyres provide traction by two methods, firstly by mechanical traction which I have no problem with, and secondly by Van der Waals forces. Do Van der Waals forces play a major part in the traction provised by rubber tyres?? Any comments apricated, Thanks

Sounds like a load of… don’t think that’s correct, friction would be a good article to read up on the topic though. --Van helsing 21:33, 25 June 2007 (UTC)

[edit] Nomenclature

Somebody said that London forces are incorrectly referred to as Van der Waals forces. This is an example of an interesting point that touches on more Wikipedia articles. Who or what determines what nomenclature is correct? Personally I would take the stance of modern dictionary writers: describe what you observe, not what you think should be observed. If one finds "Van der Waals force" in the literature as synonym for "London force", then who is to say that it is incorrect? Maybe after some IUPAC or SI committee has made a decision? But then we should definitely refer to this decision in our disapproval.--P.wormer 07:57, 6 July 2007 (UTC)

The solution is simple: such statements should be attributed to a source or removed. So I agree that removing it was correct. If I may venture a guess, I would say that equating London forces with Van der Waals forces could be seen as incorrect in the sense that one could consider VdW forces to include a repulsion term, while London forces refer only to the attractive interaction. --Itub 08:16, 10 July 2007 (UTC)

[edit] Fraught with Errors

The VDW page is fraufht with minor errors that add up to a misleading article.—Preceding unsigned comment added by 151.199.239.37 (talk • contribs)

It would be helpful if you could address which concerns you have in particular, thanks. --Van helsing 17:54, 7 July 2007 (UTC)

[edit] Needs an intro section

This article is impenetrable and needs an intro section such as this Frostburg article I found. —Preceding unsigned comment added by Feldon23 (talk • contribs)

I did a rewrite, put a link to the Frostburg article, and wrote an e-mail to its author (asking him to remove a sentence in which he suggests that the Van der Waals force is short-ranged).--P.wormer 12:56, 31 July 2007 (UTC)

[edit] London forces weaker than permanent dipole-dipole interactions?

“London forces are also present in polar molecules, but they are usually only a small part of the total interaction force....In vacuum, London forces are weaker than other intermolecular forces such as ionic interactions, hydrogen bonding, or permanent dipole-dipole interactions.”

I suggest that the article should mention that different sources give opposite answers to the question of the relative strength of London forces in polar molecules.

Linus Pauling, Van der Waals Forces. Melting Points and Boililng Points, pg 394, General Chemistry, Dover, 1970 "The theory of van der Waals force of attraction between molecules was developed by the physicist F. London in 1929. It had been suggested that the van der Waals attraction between two HCL molecules (or other molecules with a permanent dipole moment; Section 6.8) was the result of the interaction of the permanent dipole moments. Careful calculations of this energy of attraction for two HCl molecules, however, gave a result only 10% of the observed interaction energy. Moreover the interaction energy of molecules of xenon (boiling point -107 degrees C) is nearly as great as that of molecules of hydrogen chloride (boiling point -84 degrees C), although the molecules of xenon, which are single atoms, have no permanent electric dipole moment."

"van der Waals forces." Encyclopædia Britannica. 2007. Encyclopædia Britannica Online. 25 Nov. 2007 <http://www.britannica.com/eb/article-9074766>. “These specific interactions, or forces, arising from electron fluctuations in molecules (known as London forces, or dispersion forces) are present even between permanently polar molecules and produce, generally, the largest of the three contributions to intermolecular forces.”

Intermolecular Bonding - Van Der Waals Forces, ChemGuide, Jim Clark http://www.chemguide.co.uk/atoms/bonding/vdw.html “Surprisingly dipole-dipole attractions are fairly minor compared with dispersion forces, and their effect can only really be seen if you compare two molecules with the same number of electrons and the same size. [He then gives examples.]

However, other reputable sources give the same answer currenty used in this article (which is the answer I remembered from the chemistry class I took back in 1968):

Paul Foglino, London Dispersion Forces, pg 47, Cracking the AP Chemistry Exam, 2006-2007 Edition, The Princeton Review, Random House. “London dispersion forces are even weaker than dipole-dipole forces”

Joseph A. Mascetta, London Forces, pg 52, Chemistry the Easy Way, Third Edition, Barron’s, 1996 “London forces are about one tenth the force of most dipole interactions and are the weakest of all the electrical forces that act between atoms or molecules” [This might be an accidental inversion of Pauling’s summary of London that permanent dipole interactions were “only 10% of the observed interaction energy”]

When reputable sources disagree, an encyclopedia should not attempt to choose the best answer. Instead it should inform the readers of the disagreement. Ray Eston Smith Jr (talk) 20:15, 25 November 2007 (UTC)

Surely the point here is that London Forces depend on the size of the molecule. The force between two polymer chains in parallel is very large indeed. --Bduke (talk) 21:38, 25 November 2007 (UTC)

HCl is one of the smallest polar molecules. But even in HCL, the permanent dipole accounts for only 10% of the total van der Waals force. My point is that a lot of sources are providing wrong information about the relative strength of London forces vs permanent-dipole forces. I think even if this article gave the correct information, it would still be misleading if it didn't point that many sources disagree. Ray Eston Smith Jr (talk) 18:53, 26 November 2007 (UTC)

[edit] Make up your mind about capitalization of Van when it appears in the middle of the sentence.

Although I am Dutch and know the rules, I am not going to be precious about it, and just ask the head author to adopt the same convention throughout. —Preceding unsigned comment added by 137.205.183.4 (talk) 09:32, 21 February 2008 (UTC)

Done. But remember that there's no "head author"--anyone can fix errors, including you! --Itub (talk) 10:07, 21 February 2008 (UTC)