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I'm not a chemist (still in high-school), but shouldn't this read PV = nRT? :-\ /splintax
afn
When a word is quoted in a definition, it is a signal, first, that the reader should not take the meaning of the quoted word literally, and second, that the author already has or soon will clarify what is meant by the quoted term.
Unfortunately, the author never did explain why he was not satisfied with the word "occupied" when referring to the volumetric space taken up by a molecule at a given position. If the word is not "occupied", then what word is it?
This may appear to be a minor quibble, but it is far from it: this entire article is ABOUT measuring the space taken up by a molecule -- and that figures quite fundamentally in our understanding of the natural world. The author may believe he is in possession of an inexpressible subtlety of molecular mechanics, and is using the quoted word to signal such priestly knowledge. If so, forget it! Wikipedia/Chemistry is all about elegantly expressing the what is known and unknown about our material world, so that the common man may better appreciate its majesty and order.
Inquiring minds, including but not limited to my own, want to know: does a molecule occupy space or not? There is a suggestion here to the contrary, and I find that profoundly disturbing. Contrablue ( talk) 02:15, 10 February 2011 (UTC)
How does one find this radius, is there an equation to find it? The equation on this page doesn't seem to have the "radius" as a variable. Fresheneesz 03:19, 1 June 2006 (UTC)
I'm not a chemical scientist, in fact, I am far from being one, so correct me if I am wrong. I noticed the values for some of the chemicals listed on the right on the top of the page seem a little wrong. In one of the papers I am using, most of the VDW radii are identical, except Fluorine (F), Phosphorus (P), Sulfur (S), and Chlorine (Cl), and I don't have the value for copper. I then checked up on the individual pages for all the listed chemicals, and realised the radii listed on those pages are the same as mine (except copper, which is missing from my records). On the individual pages, F has a radius of 1.47 A compared to the listed 1.35, 1.80 compared to 1.9 for P, 1.80 compared to 1.85 for S, and 1.75 compared to 1.8 for Cl. Can the maintainer of the page please correct them. Thanks! Wpliao ( talk) 04:21, 31 July 2008 (UTC)
What's all the stuff about an ideal gas doing in the stub about van-der-waals radii? Just because it includes the name of van der Waals, doesn't mean it's related - I'm removing that part for now, if you think there is a justification to keep it in _this_ article, then rewrite it such that the connection becomes obvious Iridos ( talk) 23:26, 23 September 2008 (UTC)
Guess from your lack of answer that you at least don't dislike my last restructuring, then and don't think any further changes are necessary at the present time (or of course you're just too busy with something else). I'm rather content with the change of the rearrangement (although there are probably still many details that could be improved) putting the VDW-equation-part under the heading 'Methods of Determination' immediately makes clear where this is going, your example neatly demonstrates the application and this also got rid of the "other methods of determination" heading. (Perhaps I'm a bit too focused on document structure sometimes [I suspect that might come from writing in latex] but for me things are expressed much clearer now) Iridos ( talk) 08:39, 29 September 2008 (UTC)
There doesn't appear to be a formal definition of the van der Waal's radius here. The introduction states that they can be used to model physical properties of atoms and molecules, but then goes on to talk about the van der Waal's volume and never gives a formal definition. —Preceding unsigned comment added by Joshdkatz ( talk • contribs) 23:22, 16 September 2009 (UTC)
http://www.ncbi.nlm.nih.gov/pubmed/12968888
Abstract
Just granpa ( talk) 14:24, 20 November 2010 (UTC)
I read in the present article: "For helium, b = 23.7 cm3/mol. Helium is a monatomic gas, and each mole of helium contains 6.022×1023 atoms... Therefore the van der Waals volume of a single atom Vw = 39.36 Å3, which corresponds to rw = 2.11 Å."
A 4x factor seems to be missing from the equation: another article ( /info/en/?search=Van_der_Waals_equation#Conventional_derivation) states that "The excluded volume b is not just equal to the volume occupied by the solid, finite-sized particles, but actually four times that volume" and goes on explaining why.
After dividing b by four, I find rw = 1.33 Å, which is closer to the Van der Waals radius found in other sources (1.40 Å), for example http://www.webelements.com/helium/atom_sizes.html
Can somebody a bit more experienced than me look into that? Cvereb ( talk) 23:54, 13 December 2014 (UTC)
Graphs are unavailable due to technical issues. There is more info on Phabricator and on MediaWiki.org. |
Just granpa ( talk) 10:15, 10 August 2017 (UTC)
Space
Pushpa R Waghmare ( talk) 16:54, 14 November 2017 (UTC)
This article is rated B-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||
|
I'm not a chemist (still in high-school), but shouldn't this read PV = nRT? :-\ /splintax
afn
When a word is quoted in a definition, it is a signal, first, that the reader should not take the meaning of the quoted word literally, and second, that the author already has or soon will clarify what is meant by the quoted term.
Unfortunately, the author never did explain why he was not satisfied with the word "occupied" when referring to the volumetric space taken up by a molecule at a given position. If the word is not "occupied", then what word is it?
This may appear to be a minor quibble, but it is far from it: this entire article is ABOUT measuring the space taken up by a molecule -- and that figures quite fundamentally in our understanding of the natural world. The author may believe he is in possession of an inexpressible subtlety of molecular mechanics, and is using the quoted word to signal such priestly knowledge. If so, forget it! Wikipedia/Chemistry is all about elegantly expressing the what is known and unknown about our material world, so that the common man may better appreciate its majesty and order.
Inquiring minds, including but not limited to my own, want to know: does a molecule occupy space or not? There is a suggestion here to the contrary, and I find that profoundly disturbing. Contrablue ( talk) 02:15, 10 February 2011 (UTC)
How does one find this radius, is there an equation to find it? The equation on this page doesn't seem to have the "radius" as a variable. Fresheneesz 03:19, 1 June 2006 (UTC)
I'm not a chemical scientist, in fact, I am far from being one, so correct me if I am wrong. I noticed the values for some of the chemicals listed on the right on the top of the page seem a little wrong. In one of the papers I am using, most of the VDW radii are identical, except Fluorine (F), Phosphorus (P), Sulfur (S), and Chlorine (Cl), and I don't have the value for copper. I then checked up on the individual pages for all the listed chemicals, and realised the radii listed on those pages are the same as mine (except copper, which is missing from my records). On the individual pages, F has a radius of 1.47 A compared to the listed 1.35, 1.80 compared to 1.9 for P, 1.80 compared to 1.85 for S, and 1.75 compared to 1.8 for Cl. Can the maintainer of the page please correct them. Thanks! Wpliao ( talk) 04:21, 31 July 2008 (UTC)
What's all the stuff about an ideal gas doing in the stub about van-der-waals radii? Just because it includes the name of van der Waals, doesn't mean it's related - I'm removing that part for now, if you think there is a justification to keep it in _this_ article, then rewrite it such that the connection becomes obvious Iridos ( talk) 23:26, 23 September 2008 (UTC)
Guess from your lack of answer that you at least don't dislike my last restructuring, then and don't think any further changes are necessary at the present time (or of course you're just too busy with something else). I'm rather content with the change of the rearrangement (although there are probably still many details that could be improved) putting the VDW-equation-part under the heading 'Methods of Determination' immediately makes clear where this is going, your example neatly demonstrates the application and this also got rid of the "other methods of determination" heading. (Perhaps I'm a bit too focused on document structure sometimes [I suspect that might come from writing in latex] but for me things are expressed much clearer now) Iridos ( talk) 08:39, 29 September 2008 (UTC)
There doesn't appear to be a formal definition of the van der Waal's radius here. The introduction states that they can be used to model physical properties of atoms and molecules, but then goes on to talk about the van der Waal's volume and never gives a formal definition. —Preceding unsigned comment added by Joshdkatz ( talk • contribs) 23:22, 16 September 2009 (UTC)
http://www.ncbi.nlm.nih.gov/pubmed/12968888
Abstract
Just granpa ( talk) 14:24, 20 November 2010 (UTC)
I read in the present article: "For helium, b = 23.7 cm3/mol. Helium is a monatomic gas, and each mole of helium contains 6.022×1023 atoms... Therefore the van der Waals volume of a single atom Vw = 39.36 Å3, which corresponds to rw = 2.11 Å."
A 4x factor seems to be missing from the equation: another article ( /info/en/?search=Van_der_Waals_equation#Conventional_derivation) states that "The excluded volume b is not just equal to the volume occupied by the solid, finite-sized particles, but actually four times that volume" and goes on explaining why.
After dividing b by four, I find rw = 1.33 Å, which is closer to the Van der Waals radius found in other sources (1.40 Å), for example http://www.webelements.com/helium/atom_sizes.html
Can somebody a bit more experienced than me look into that? Cvereb ( talk) 23:54, 13 December 2014 (UTC)
Graphs are unavailable due to technical issues. There is more info on Phabricator and on MediaWiki.org. |
Just granpa ( talk) 10:15, 10 August 2017 (UTC)
Space
Pushpa R Waghmare ( talk) 16:54, 14 November 2017 (UTC)