Talk:Avogadro constant/Archive 2

Archive 1

Archive 2

Unit cell volume

Despite having been undone by User:SpinningSpark, the correction made to the calculation of the unit cell volume is actually correct. The previous author had converted from $d_{220}$ to the lattice parameter a incorrectly, resulting in a volume that was wrong by three orders or magnitude. Qmonkey (talk • contribs) 12:49, 24 April 2009 (UTC)

Agreed, though it took me an age to be convinced you were right. SpinningSpark 17:17, 24 April 2009 (UTC)

It could have been who made the mistake, but it is clear that d₂₂₀ is not the lattice parameter, so the error is completely plausible (and would be of about the size that Qmonkey refers to). The present value, 12.058 8349(11) cm³mol⁻¹, is correct according to NIST, and I've added the ref to the article. Physchim62 (talk) 19:10, 24 April 2009 (UTC)

Constants in Tex format

I agree that the use of Tex is overdone. It's pretty, but it can't be copied and pasted to a calculator. The dual listing is an alternative, but it is contrary to the purpose of using Tex: To make it pretty. And maintenance becomes an issue. The powers that be already changed it from 6.023e23. They probably aren't done "fixing" it.

How about using larger and bolded text:

6.02214179(30)e+23

- Ac44ck (talk) 04:01, 15 May 2009 (UTC)

No! Yeuk, please don't do that. By the way, there are no "powers that be" here, only guidelines. It was user User:Physchim62 who removed the Tex. As far as I know, he has no special powers and is not one of the X-men. Personally, I liked the Tex version. SpinningSpark 19:01, 15 May 2009 (UTC)

"The X-Men are a fictional superhero team" [3] If just asked my life-partner, and she says I'm neither; although she sometimes wishes I were one or the other… When Ac44ck speaks of the "powers that be", I assume that s/he was talking about either this cabal or this cabal, not The Cabal That Most Definitely Does NOT Exists, Honest Guv'. It's actually quite possible that the value of the Avogadro constant will be fixed (for SI) in the near future, but not before 2011.

If this numerical value is so important, why is wrapped behind a PNG image? Like, you want to say this number is really important so look at File:Avogadro constant image.png to see what it is! You can't copy-paste it, mind, you'll just have to use an old-fashioned pencil-and-paper if you want to write the number down. Oh, and sorry if you're using a screen-reader or portable device to access Wikipedia, we can't guarantee that you'll be able to access this vital information at all. But we think it looks nice, so there.

There is absolutely NO reason to use TeX for these simple equations defining the values of physical constants. There are plenty of reasons not to use TeX, from accessibility, to esthetics, to plain common sense in non making things more complicated than they need to be. If you think the numerical value is not sufficiently prominent in the article, then find some other way to highlight it (such as a short infobox, as is used for other physical constants). If you really think that this is a solution, then I'm sorry for you. Physchim62 (talk) 22:39, 15 May 2009 (UTC)

If cut and paste is the issue, HTML won't do either (at least when there is an exponent--131.174.224.201 (talk) 10:25, 16 May 2009 (UTC)

That depends where you're pasting it too. Physchim62 (talk) 11:51, 16 May 2009 (UTC)

Looking for someone to teach a brief lesson

Avogadro's Constant (or as I had learned it, Avogadro's Number) was something I retained briefly while in my last year of high school. Much the same way I study vocabulary (grueling repetition until temporary memory retention occurs) I believe I have lost most of the memory pertaining to this concept. Am I correct to assume that Avogadro has added a fourth dimension to measurement (the mass volume density category)? One that measures quantity? I understand that I will most-likely appear to be a fool, but without a chemistry textbook at hand I'd very much appreciate an in-depth explanation of Avogadro's Number, the mol, and its use in chemistry. If anyone would be willing to contribute to this cause, please send whatever you are willing to my user talk page! I would love even a basic (first chemistry class sort of deal) understanding of this concept since it is essential in many fields of science. Any help would be much appreciated! Robert M Johnson (talk) 15:48, 23 June 2009 (UTC)

http://www.nist.gov/public_affairs/newsfromnist_beyond_the_kilogram.htm

The SI is founded on seven base units—the meter, kilogram, second, ampere, kelvin, mole, and candela (corresponding to the seven base quantities of length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity).

There may be more than four dimensions to measurement if the seven units of SI are independent.-Ac44ck (talk) 02:34, 24 June 2009 (UTC)

Remarkable.... how ignorant someone (infatuated with science) can be until its all put on the table in front of him. Thank you. Robert M Johnson (talk) 09:51, 24 June 2009 (UTC)

Anachronistic?

How is the phrase "Avogadro's Number" anachronistic? Was he alive before the discovery of numbers?

Exactly. I wanted someone else to agree with me before I removed it. I believe the author wanted to use a word like "archaic", but if that word were to be there, I think it would need a good source. Feel free to remove the word entirely.  :)Luminifer (talk) 04:32, 24 June 2009 (UTC)

It also appears on the page Mole (unit). Robert M Johnson (talk) 09:54, 24 June 2009 (UTC)

The term "Avogadro's Number" is anachronistic, for at least two reasons:

• It isn't a pure number: it is a physical constant with dimensions. The numerical value of the constant is entirely dependent on the system of units used to measure it. It is perfectly correct to say that the Avogadro constant is roughly 2.7×10²⁶ lb-mol.⁻¹
• The constant doesn't belong to Avogadro, it was named in his honour nearly a century after Avogadro's paper. Avogadro himself died (at least) five years before the first order-of-magnitude estimation of the constant that now bears his name. If you look at the CODATA references in the article, you will find that current practice is not to use a possessive form in the names of physical constants.

We can't say that the term "Avogadro's Number" is archaic or obsolete, because it is still widely used. We can say that it's wrong. Physchim62 (talk) 10:59, 24 June 2009 (UTC)

• This may be true, but if you look at Anachronism, neither of your points actually have anything to do with what an anachronism is. The word does not apply to something used commonly, even if incorrectly. Luminifer (talk) 14:17, 24 June 2009 (UTC)

I completely agree with what you are saying, however its context on the page appears, to the average wiki user, as an incorrectly used adverb. Perhaps adding what knowledge you have just imparted to the page itself would clarify. (just a thought) Robert M Johnson (talk) 13:24, 24 June 2009 (UTC)

I've added a new paragraph to the article explaining why "Avogadro's number" is a bad name these days – I even managed to find a ref from Paul de Bièvre (a pretty big fish in this particular pond), which excellently explains the change, and the controversy it caused at the time: I recommend it to anyone who's interested in such details! Physchim62 (talk) 07:49, 25 June 2009 (UTC)

Thank you! Beautiful work... and with a Bonus! I'm about halfway through reading it now! Your help is very-much appreciated! Robert M Johnson (talk) 14:48, 25 June 2009 (UTC)

I would still like to replace the incorrect word "anachonistically". I suggest "inaccurately". Luminifer (talk) 20:50, 26 June 2009 (UTC)

I'm going to do it unless anyone objects or gets to it first.. Luminifer (talk) 17:02, 27 June 2009 (UTC)

"Inaccurate" would be wrong, as the term "Avogadro's number" is only understood with a single meaning. "Anachronistic" is the correct adjective, as it refers to a different time period. Physchim62 (talk) 18:04, 27 June 2009 (UTC)

"archaically"? SpinningSpark 19:03, 27 June 2009 (UTC)

If you look at the wikipedia article for anachronistic, it is pretty clear that it is not the correct term. Many people still call it Avogadro's number, so it is not a temporal inaccuracy for someone to still use the phrase. Archaic has the same problem (generally anachronisms refer to inconsistencies where a future term is used in the past, but it can be used both ways. archaic refers only to past terms used in the present). I am led to believe that "inaccurately" is not incorrect, as the whole point is that "Avogadro's number" is not actually a "number", but a constant. Luminifer (talk) 05:03, 28 June 2009 (UTC)

Well it is a temporal inaccuracy to use "Avogadro's number": just because many people still use the term doesn't make it less of an error. Many people break the speed limit, but that doesn't make it legal! And "anachronistic" doesn't only refer to modern terms used in a past setting; it can also refer to archaic terms being used in a modern setting. It would be anachronistic to refer to Gordon Brown as a "British subject", for example. Physchim62 (talk) 10:35, 28 June 2009 (UTC)

I actually said in what you replied to that anachronisms can be used both ways - I'm sorry, but did you actually read what I wrote? The problem is that the term is still in usage, which means it cannot be an anachronism. Go read the article on anachronisms, and you'll see that it cannot be used for terms in common usage. Luminifer (talk) 14:38, 28 June 2009 (UTC)

Now you're just trolling. You don't agree with the definition of "anachronistic" and so you want to shout about. Please do it elsewhere. Physchim62 (talk) 18:32, 28 June 2009 (UTC)

I agree with the definition on wikipedia, which does not apply to the usage here. I am not the only one who disagreed - see the comment at the top of this thread. Please do not accuse me of things in lieu of actually presenting somewhere that supports your definition. Luminifer (talk) 03:57, 29 June 2009 (UTC)

I think it's time for an informal poll. Who believes that the word 'anachronistically' is the word that should be used here, and who believes that it is not? Luminifer (talk) 04:13, 29 June 2009 (UTC)

Would the term parachronism apply here?? Robert M Johnson (talk) 04:54, 29 June 2009 (UTC)

I'm not entirely sure. Part of my issue with this is that, only 10 years ago, I learned this as Avogadro's Number in school. It's hard to imagine that something like anachronism can apply to something that was at the very least taught in schools 10 years ago. I think we'd need a pretty hardcore citation to prove that it's no longer used by most people on the planet, as it was in incredibly common usage not long ago, and the first I heard of the name being changed was actually hear. This is why I suggest that we should have a word that says what we really mean - that the name "Avogadro's number" is inaccure, as it is a constant (with units), not a simple number. Luminifer (talk) 06:11, 29 June 2009 (UTC)

To borrow from another topic on this talk page, perhaps 6.023e23 is Avogadro's Number and 6.022e23 is the Avogadro constant. ;-) - Ac44ck (talk) 01:07, 1 July 2009 (UTC)

A similar example: I don't think one would say that Pluto is anachronistically referred to as a planet. Luminifer (talk) 06:14, 29 June 2009 (UTC)

It is not an anachronism to refer to Pluto as a planet, even if it is no longer considered a planet. If Plato had Socrates discussing whether Pluto should or should not be considered a planet, THAT would be an anachronism. It is a comment that is known to be a fiction since it could not have happened at the time under consideration. I am sure others have noted this, but I can't stop myself. ( Martin | talk • contribs 22:43, 20 November 2013 (UTC))

If we are to keep 'anachronistically', we definitely need a good citation to show that the phrase "Avogadro's number" is not currently used anywhere. I am not removing it, just putting an OR tag because it is original research if there is no citation to back it up.Luminifer (talk) 17:41, 30 June 2009 (UTC)

That isn't the meaning of "anachronistic": that would be "archaic". There is already a reference which explains when and why the terminology changed. The only original research going on is Luminifer's rewriting of the English language. Physchim62 (talk) 08:36, 1 July 2009 (UTC)

From wikipedia's page anachronism: An anachronism—from the Greek ανά (ana: against, anti-) and χρόνος (chronos: time)—is an error in chronology, especially a chronological misplacing of persons, events, objects, or customs in regard to each other. The item is often an object, but may be a verbal expression, a technology, a philosophical idea, a musical style, a material, a custom, or anything else so closely associated with a particular period in time that it would be incorrect to place it outside its proper domain.. How does this apply? Luminifer (talk) 15:33, 1 July 2009 (UTC)

Also, for the record, I would appreciate if you would stop with the accusatory language. You may not have noticed I did not start this discussion thread - I merely joined it. Luminifer (talk) 15:39, 1 July 2009 (UTC)

You could try citing a dictionary for your definition: it's something I've done in the this discussion, but which you have singularly failed to do. Physchim62 (talk) 20:54, 2 July 2009 (UTC)

I've been asked to comment here; my last math class was a loooooong while ago, so I bring no mathematical insights here. But as a naive reader, I will say that the current phraseology, including the "(anachronistically)" seems a bit odd. It makes me ask a question, rather than inform me as a lead should do. I realize that the information about the old name is in the text, but a good lead should summarize the article and be able to stand alone, and currently I feel I am left hanging asking "why is it anachronistic?". It seems that the IP that started this conversation felt something similar.[4] Suggestion....Could you remove the word in parenthesis from its current position, and instead add a brief sentence explaining that Avogadro's number is also sometimes used and why it doesn't fit the bill?--Slp1 (talk) 11:52, 2 July 2009 (UTC)

The very first paragraph (after the lede) is devoted entirely to that. I don't see why the lede should be encumbered simply for the benefit of people who are unwilling to read the article that it [the lede] is summarizing. The summary is that "Avogadro's number" is an anachronistic term, although still used in many texts. The explanation comes later, as it is less important. Physchim62 (talk) 20:54, 2 July 2009 (UTC)

Well, WP:LEAD says something a bit different about forcing people to read on. "The lead should be able to stand alone as a concise overview of the article". It also seems clear from the comments of various editors that while "anachronistic" may summarize the issue well for you, it doesn't for several others editors, (including this one). Given that the terminology issue gets a paragraph in the main text, a short sentence would be quite reasonable in the lead, no? --Slp1 (talk) 22:30, 2 July 2009 (UTC)

Perhaps the wording can be factual without appearing so loaded to some. How about something like the following?

The Avogadro constant (symbols: L, N_A) is the number of "elementary entities" (usually atoms or molecules) in one mole, that is (from the definition of the mole), the number of atoms in exactly 12 grams of carbon-12. It was orignially called Avogadro's number. The 2006 CODATA recommended value is:

That doesn't rule out the fact that it is still called "Avogadro's number" by some. Note the entry for Santa Claus:

Santa Claus, also known as Saint Nicholas, Father Christmas, Kris Kringle or simply "Santa", is ...

Who wants to go there and proclaim "Saint Nicholas" (dead for 16 centuries) as a reference to Santa Claus "anachronistic"? -Ac44ck (talk) 01:59, 3 July 2009 (UTC)

It's late at night here, but certainly to my eyes right now this seems like a nice solution! Luminifer (talk) 07:09, 3 July 2009 (UTC)

Completely inacceptable there's a spelling mistake! No, I can live with that phrasing, which is accurate. Physchim62 (talk) 10:58, 3 July 2009 (UTC)

And, two months later...I suspect that the people supporting "anachronistic" didn't fully understanding the meaning of the word because the definition in Wiktionary is somewhat lacking. Anachronism doesn't mean "used in the wrong time period", it means "shown to have been used before the item or idea could have existed". Anachronism can not exist in real life, only in literature (in the larger sense, including books of history, dramas, movies, etc.). Using "Avogadro's number" when the current phrase is "Avogadro's constant" is not anachronistic: having Julius Caesar use the phrase "Avogadro's number" in a movie would be an example of anachronism because Caesar could never have known about Avogadro or his constant, because Avogadro was born long after Caesar died. If something is possible, it is not and cannot be anachronistic. --NellieBly (talk) 20:04, 16 October 2009 (UTC)

Discussing whether the name is anachronistic is well and good for the talk page, but the article should be consistent in style with the articles for other constants named after famous people, like Euler constant, Planck constant, etc. These articles say that the possessive forms (e.g., Planck's constant) are "also" used, and not "formerly" used, as this article did, and I've changed this article to match.

Also, I removed these sentences:

The change in name from the possessive form "Avogadro's" to the nominative form "Avogadro" is a general change in practice since Perrin's time for the names of all physical constants. In effect, the constant is named in honour of Avogadro: he does not own it, and it would have been impossible to measure it during Avogadro's lifetime.

The 'he does not own it' reasoning sounds like original research (Robert Hooke doesn't own Hooke's Law, either, but no one says "Hooke Law"), but worse, the footnoted source fails verification---it uses the term "Avogadro constant" but doesn't discuss why, or assert that its usage reflects a general change from Perrin's practice. I removed the sentences because of the failed verification. -- Heath 198.82.28.195 (talk) 19:00, 21 April 2010 (UTC)

References

History of Avogadro's number needs expansion -- esp. Einstein's contribution to determining value

There isn't a lot here about how the number was actually calculated. A couple different people were involved, but one of the major contributors was Albert Einstein, through his breakthrough paper on Brownian motion.

See,http://web2.uwindsor.ca/courses/physics/high_schools/2005/Brownian_motion/contributions4.html for a brief summary of this.

Other general history about its origins would be useful as well. —Preceding unsigned comment added by 76.65.22.16 (talk) 18:01, 18 October 2009 (UTC)

Archiving

The discussion about the value of the Avogadro constant has been moved to the Archives.

I think that was a mistake, because there is no equivalent content in the article, explaining why those of us who were at school in the 70's or earlier all learned that Avogadro's number is 6.023 * 10^23

I have to agree, I think the fact that it actually was "Avogadro's number - 6.023 * 10^23" is very helpful to those of us who learned this other number (late 80's was my last chem class), and who are now confronted with this new "constant" value. This was the only place I found this. Thanks. (71.146.18.207 (talk) 01:02, 3 November 2010 (UTC))

It was alright when the content was here in Talk, justifying the content on the main page, but now it's just missing information. —Preceding unsigned comment added by 203.206.162.148 (talk) 09:48, 12 May 2010 (UTC)

All active talk pages eventually get archived on Wikipedia. They cannot be used to permanently store information (although it is still in the archive), or to record unsourced alternative versions of an article as some occassionally try to do. Those parts of the discussion for which there are sources can be turned into a history section in the article. Feel free to do that yourself if you like. Those parts of the discussion which cannot be sourced have no place on Wikipedia in any case. As for justifying the content, the source of the current value is given in the article and there is no more justification than that required. SpinningSpark 20:42, 12 May 2010 (UTC)

Well, that is an interesting point of view, but clearly I disagree with you. See Jesus and {{FAQ}} for alternatives. —Preceding unsigned comment added by 203.206.162.148 (talk) 09:06, 8 September 2010 (UTC)

Avogadro's number vs. Avogadro constant

Reference [2] correctly defines the Avogadro constant:

Avogadro constant L, NA mol-'

Number of entities in a system divided by the amount-of-substance of those entities (1 1).

NOTE L = N/n = 6,022 136 7(36) x 10E23 /mol

It would make sense to start out with the official definition. The article goes on to equate Avogadro's number with the Avogadro constant, which is inaccurate.

In fact, in many wikipedia articles (Chemistry, Mole (unit), Amount of substance, Avogadro constant), there is confusion about the units of Avogadro's number N₀ (should be dimensionless) and the Avogadro constant N_A (dimension 1/mol). These are two different constants and should not be used as synonyms. The Avogadro constant is an official physical constant used in the SI system to convert between Amount of substance and number of entities. Because it has a unit, it is not a number. It appears in conversion of macroscopic properties (quantity per mole) to atomic properties (quantity based on a single atom or molecule).

Avogadro's number was used widely before the unit mole for the quantity amount of substance was added to the basic SI units in the early seventies. Textbooks and teachers have not all fully made this transition, especially when it comes to problem sets and model answers. You will find many instances of the statement 1 mol = 6.022x10E23, but according to the current definitions, that statement is wrong. Saying that the name Avogadro's number was changed to the Avogadro constant is also wrong. It was a switch to different units necessitated by the new system of base units. They do have the same numeric values when using mole as the unit, but they have different dimensions, so they are different.

I'll check in a couple of days to see if anyone wishes to comment, and then revise the article accordingly if there is no objection. Theislikerice (talk) 00:51, 18 August 2010 (UTC)

I concur with the editor. The previous definition was simply wrong by modern standards and I have rewritten the lede accordingly. The new prose is directly supported by the (already present) reference cited. Kbrose (talk) 01:34, 18 August 2010 (UTC)

You might like to read the long section above, in which some editor objected to the phrase that the term "Avogadro's number" is anachronistic: there are many people who have never quite digested the fact that amount of substance is an independent dimension at macroscopic scales. You can find several similar arguments at Talk:Mole (unit), where people seem to believe that the mole is defined as 6.022×10²³ atoms or molecules when in fact it has never been defined in that way (although it might be redefined that way from next year).

"Avogadro's number" was never a true pure number; it should always have been a constant with units of g-at.⁻¹. You can tell it's a dimensional constant because it's value depends on the units used to measure it, and so changed in 1960 when carbon-12 scale was adopted for atomic weights instead of the oxygen scale. However, amount of substance is such a fundamental concept in chemistry (it predates Dalton's atomic theory, for example) that chemists took a long while to think of it in terms of a quantity dimension, until they realized that you couldn't express a whole range of chemical quantities in the SI without a new base unit. Even today, I doubt there is one in a hundred practicising chemists who could write a dimensionally homogeneous equation to calculate a molar mass!

Well, if that is the case, here is one attempt (for the more than 99/100 practicing chemists who want to learn):

Molar mass is the mass of a pure substance divided by the chemical amount of that substance

m_Water = m_{sample of water}/n_{sample of water} = 180 g / 10 mol = 18 g/mol

That might be even better than the current Wikipedia definition, which seems to suggest that the molar mass has the dimension of mass. There is a subtle difference between "the mass of one mole" and "the mass per chemical amount", and the latter is correct because it arrives at the correct dimensions and is independent of choice of units.Theislikerice (talk) 13:51, 18 August 2010 (UTC)

Molar mass, symbol M, is the mass of one mole of a substance (chemical element or chemical compound). It is a physical property which is characteristic of each pure substance. The base SI unit for mass is the kilogram but, for both practical and historical reasons, molar masses are almost always quoted in grams per mole (g/mol or g mol⁻¹), especially in chemistry.

When Perrin first measured the constant, he called it "Avogadro's number" and expressed it as a pure number simply because he didn't recognize amount of substance as a separate dimension. There's nothing unique about that: in CGS electromagnetic units, μ₀ is a pure number (and equal to one, so ignored) simply because the inventors of the system didn't recognize the need for a fourth dimension to coherently deal with electromagnetic quantities (they thought they could get away with the three "traditional" dimensions, hence CGS).

With increasing sophistication in the theory of systems of units, it was recognized that N_A had dimensions and hence units, and so should be called the "Avogadro constant", just as it was realized that μ₀ had dimensions and hence units. But that doesn't mean there is some beast called "Avogadro's number" which is still lurking out there and which is different from the Avogadro constant! Both terms relate to the same concept, it's just that one is more correct than the other in terms of our modern understanding of unit systems. To pretend that they are two different things is to muddy the waters even more, and leads to problems such as the current "definition of Avogadro's number" in the article, which has never been a correct definition: "Avogadro's number" is simply outdated terminology for the Avogadro constant, based on a misconception of the relevant dimensions. Physchim62 (talk) 10:07, 18 August 2010 (UTC)

The term is still in wide-spread use, and indeed is often referred to when the count of entities is required. I don't think it's appropriate for WP to decide what is obsolete and not. We state and emphasize what the standards say, and mention the common usage as well, as there is a lot of secondary literature that people can quote to justify it. Kbrose (talk) 15:53, 18 August 2010 (UTC)

Saying that Avogadro's number is outdated terminology with an outdated choice of units seems a fine approach to me. Then, however, you have to make sure nobody writes about the number of entities in a mole, but rather about the number of entities per amount of substance. Yesterday, Chemistry, Mole (unit), Amount of substance, Avogadro constant all had inaccurate language in the lede (sometimes contradicting the correct statements in the body). On the other hand, some people in the field want to keep using N₀ and are trying to find a new name for it so that the waters aren't muddied. Either approach is fine for the experts, but if there is such a persistent misconception in the minds of so many, the true definitions ought to be spelled out in Wikipedia loud and clear in a way everyone can understand them, and the misconceptions should be noted as well. Right now, Avogadro's number redirects to Avogadro constant. To the novice, that would imply they are the same. Maybe Avogadro's number should have its own entry, "outdated terminology for the Avogadro constant, which has different units".Theislikerice (talk) 13:51, 18 August 2010 (UTC)

It is perfectly ok for these two terms to direct to the same article, especially when they are so closely related. It would be historically and factually incorrect to separate them. The history needs explanation as it dictates the definitions and two articles would be a lot of duplication. I believe my (and your) edits yesterday clarify the situation sufficiently. Surely one could present more history and insight into the topic at various time in history, but that does require a bit more research in terms of reference collection. Kbrose (talk) 15:38, 18 August 2010 (UTC)

Hello Sir.Take my cordial love.I am Imtiaj from Bangladesh.I wanna discuss about Avogadro's number or constant......😊 All of you are so talented. I m weak than all of you. But I wanna say that Avogadros number has no units.All of we know, 1 mole = 6.023e23.....and we also know it that, Avogadro's constant,NA=6.023e23/mol.........If 1 mol = 6.023e23 then NA= 6.023e23/6.023e23=1.........that's mean Avogadro's constant, NA=1.......but its not true.....I m saying again that Avogadro's constant has no units...in this constant, (mol^-1) doesn't mean its unit.......I have a lot of theory to prove it that Avogadro's constant or number has no units..😊😊And there is no difference between avogadro's number and avogadro's constant........you said that 1 mol is not = 6.023e23.....you are wrong....1 mol = 6.023e23....... that's true....I m 100% sure Alhamdulillah.......😊😊😊 Imtiaj mrida (talk) 18:56, 1 September 2017 (UTC)

References

Good Article?

I am very surprised by the status of good article. Not only had it errors in its definition, but it also has fairly poor presentation style of the topic. It present the mathematical relations without much discussion necessary for a general audience. Further it is structured poorly. Too much material is lumped into the lede that is not discussed in the body of the article. A good article status review is in order.Kbrose (talk) 01:49, 18 August 2010 (UTC)

I hardly see the need to waste people's time with a good article review (the whole GA/FA system is a glorious waste of time, IMO). But before you criticize the GA reviewer too much, you should have checked if the error in the definition was in the version that passed (it wasn't).

There's plenty that could be done to improve the article, yes. The last paragraph of the lede really belongs in a "History" section, which would also cover late 19th century estimates and Perrin's measurements. Physchim62 (talk) 10:19, 18 August 2010 (UTC)

If you want to focus on just the error, you are correct. [strike that, upon rereading the old article, it also misstates the definition, as it reports the constant to be a count of particles] But the article was much the same back and had the same problems. And I agree, this is just one example that shows the state of affairs w/r/t GA. Kbrose (talk) 15:44, 18 August 2010 (UTC)

You are correct: the Avogadro constant is defined independently of the unit system that you use for amount of substance: I guess we're all so used to seeing the definition in terms of moles that we flick over the fundamental inaccuracy. I hope my current definition is better... ;) Physchim62 (talk) 16:29, 18 August 2010 (UTC)

hum, no. Avogadro contant has the dimension of inverse of amount of substance, as it is now defined by N/n, where n is the amount of substance (in mole) of a ensemble of N particles. Kbrose (talk) 18:52, 18 August 2010 (UTC)

You make my point exactly! The Avogadro constant is defined independentley of the system of units, but not of the system of dimensions. It is not simply defined in terms of moles. Physchim62 (talk) 19:30, 18 August 2010 (UTC)

The equation N/n weaves the dimension AND the unit into the definition, the unit of amount of substance is defined as the mole. If you want to give credence to other units such as gram-mole or ounce-moles, fine, but those are not used for definition. Kbrose (talk) 20:34, 18 August 2010 (UTC)

No, amount of substance is defined as a physical quantity that is proportional to the number of specified entities: the constant of proportionality is the inverse of the Avogadro constant (see IUPAC or BIPM refs. in the article). It can be measured in any unit you choose (including pure numbers, given that it is quantified at the microscopic scale). Physchim62 (talk) 21:30, 18 August 2010 (UTC)

One more point while we're collecting a wishlist for stuff to add: the Avogadro constant is likely to be given a fixed value in the relatively near future, and we should mention the discussions that are going on in that direction. It's quite a big job to cover the whole plans for remodelling SI but, as there's editor interest here, I'll try to get the refs together quickly. Physchim62 (talk) 16:29, 18 August 2010 (UTC)

Definition

We seem to have a problem with the definition of "Avogadro's number"! At the moment, it is defined as "the count of elementary entities as there are atoms in 0.012 kg of the isotope carbon-12": I feel that such a definition is incorrect for several reasons.

• The cited reference does not refer to "Avogadro's number", only to the Avogadro constant. This seems to have led the editor to believe that "Avogadro's number" must be defined as the numerical value of the Avogadro constant in moles; nevertheless, the editor has not used that definition, but one of his/her choosing.

The lede only defines the Avogadro constant as a standards-based definition and puts the term Avogadro's number in historical perspective and mentions what that was. Kbrose (talk) 20:49, 18 August 2010 (UTC)

• In attempting to define "Avogadro's number" in terms of the mole, the editor has forgotten to specifically account for binding energy and zero-point energy – a 12-gram diamond composed entirely of carbon-12 atoms is slightly less than one mole of carbon-12 atoms (not that the difference is practically important).

It does not 'define' it in the terms of the mole. It only talks about number of particles in C-12. None of the standards documents ever consider the binding energy of bound carbons. The SI has always stated that these definitions refer to unbound carbon. Kbrose (talk) 20:49, 18 August 2010 (UTC)

The CIPM had to clarify that the definition refers to unbound atoms (as is necessary from the way that relative atomic masses are determined): "0.012 kg of carbon-12" does not make it clear that you are actually talking about a number of unbound atoms at rest in their gound state which, collectively, would have a mass of 12 grams. Physchim62 (talk) 21:21, 18 August 2010 (UTC)

You're hair-splitting tactic is completely inappropriate here, then you might as well simply publish the CIPM docs here and be done with it. Here we have to draw a line somewhere; that's what references are for, for the user to find all the details that we can't mention. This has to be simple and understandable for general audience and sometimes a little beyond. Kbrose (talk) 21:37, 18 August 2010 (UTC)

• Even within the context of the almost-correct definition in terms of the mole, the definition remains tied to a single system of units, rather than being universal for all systems of units.

Isn't that true for almost all constants? Indeed that is the definition of the constant by the committees. A universal constant would be one with no unit, which has been achieved of course for many constants, but not in the current SI. Kbrose (talk) 20:49, 18 August 2010 (UTC)

No, that is not true for other physical constants. Physical constants are defined by quantity equations, which are invarient between coherent systems of units. Physchim62 (talk) 21:21, 18 August 2010 (UTC)

• The definition in terms of a number of carbon-12 atoms has never been correctly used, as the change of scale to carbon-12 from oxygen/oxygen-16 came concurrently with the acceptance of amount of substance as a separate dimension. Therefore, the only correct definitions of the term of "Avogadro's number" as a pure number are those that refer to an oxygen standard.

Again, the article does not 'define' Avogadro's number, it states what it is in historical context and mentions the reason of changes in the SI. The lede is not the place to elaborate on lengthy history, the history section should bear that out in context of the various definition used over the centuries. In historical perspective there is not any one single correct definition, it's been an evolution of changes and desires to increase the precision of the metric systems in general, not just driven by the effort to determine a single unit, but by finding the most precise and self-consistent definitions of many constants. Kbrose (talk) 20:49, 18 August 2010 (UTC)

The article already gave (and still gives) a referenced statement of Perrin's original definition. The "evolution of changes and desires" has been to say that it is not a pure number but a dimensional constant. To pretend otherwise is to muddy the waters. There is no reference from standards organizations in the last 35 years which refers to "Avogadro's number" as a pure number: they invariably refer to the Avogadro constant as a dimensional constant. Physchim62 (talk) 21:21, 18 August 2010 (UTC)

• To include a definition of "Avogadro's number" as different from the Avogadro constant implies that they refer to different concepts. They do not: the difference in dimensions comes from our human interpretation of dimensions of quantity at different periods. We do not consider that the modern magnetic constant is a different constant from the old permeability of free space simply because it has different dimensions (and, in SI units, a hugely different value).

The article does not refer to it as being different, it clearly states that they are closely related and states that relationship in historical context having originated only because of change of definitions in the SI. Kbrose (talk) 20:49, 18 August 2010 (UTC)

They are not "closely related" – they are they same concept related in different systems of units. Physchim62 (talk) 21:21, 18 August 2010 (UTC)

You can split-hairs as much as you like and start an argument now about what closely related means, but I am not going to engage in that. The article states what it means, that it is merely a redefinition of the reference system. That it is the same concept is abundantly clear and already stated. Kbrose (talk) 21:50, 18 August 2010 (UTC)

I look forward to your comments! Physchim62 (talk) 19:30, 18 August 2010 (UTC)

Maybe there shouldn't be any definition of Avogadro's number, just a comment that it is superceded. The current statement about its relationship to the Avogadro constant is also, subtly, wrong: "Avogadro's number is a dimensionless quantity and has the numerical value of the Avogadro constant." This is only true if the Avogadro constant happens to be expressed in 1/mol. If for some strange reason one should use 1/mmol or - heaven forbid - 1/lb-mol, then it would not be the same number.Theislikerice (talk) 19:46, 18 August 2010 (UTC)

An encyclopedia needs a representation of what Avogadro's number means. There are still piles of text books that speak of it, and while the definitions are not the up-to-date standards definitions, they do equally well in defining the basic concepts. Just stating that it's obsolete is a very biased view, even thought from a standards perspective that is true. After all, there are still many scientists that do not like the current definitions. An article should emphasize the current state of affairs first of course. Perhaps we should go back and simply cite the previous definitions as written in the standards documents of the time. That should indeed occur in the history section. The article further needs a new section for a self-standing treatment of definition, which I actually started last night (not here), as a good article's lede is only supposed to summarize the content, not present the only mention of content. Kbrose (talk) 21:04, 18 August 2010 (UTC)

In which case, let's just say that Avogadro's number is an old name for the same concept in a slightly different set of units, and that the difference has no practical consequence for chemistry. Physchim62 (talk) 21:25, 18 August 2010 (UTC)

Nor is it the same number that Perrin defined in terms of the oxygen standard... Physchim62 (talk) 19:50, 18 August 2010 (UTC)

The Binary Mole sets Avogadro's Constant to 24 significant digits

While Avogadro’s number is a dimensionless quantity, it is currently based on a single physical property (the defined gram, hence the golden karat). Since instruments are unable to measure that property accurately beyond 10 places it is not known to an integer value. The Binary Mole, on the other hand, defines a precise integer value for the units that occur in a mole without any such analytical attachment. Thus, the binary mole is an integer of 24 digits:

N_o = 2⁷⁹ = 604 462 909 807 314 587 353 088

or 6.0446 x 10²³ to 5-significant digits for mathematical calculations.

Since I am the originator of this definition of a mole, I am not allowed to enter it into the "Avogadro's Constant" article page. If you see the logic of it, please copy the section above from the "edit" mode and enter it for me at the end of the introductory section. There is no experimental test that can be performed as some would have me do before accepting my value. The Binary Mole flows from Avogadro's Constant being 6.0x10²³ [based on the current definition of a gram (kilogram, if you wish)] and from the logic that stems from understanding the kinetics of radioactive decay. What is clearly at issue is the reluctance of the International bodies to tweak the value of the kilogram more than a smidgen. Doing a small tweak does little in the matter. On the other hand, a 0.37% change of the kilogram to effect a 6.0221 to 6.0446 change implies that they have been shooting at the wrong target value (working on precision rather than accuracy) which is something those in power are reluctant to admit. Then there is the change in the definition of a kilogram of gold - the golden karat now dictating what science can and cannot do. Frankly, the volatility of gold in the market would obliterate any redefinition of the kilogram in a flash! So the problem is complacency of those who make the rules even in our current state of monetary flux.

The hard copy for ref [7] is: Williams, Joel M, Challenging Science (2005), Author House; the e-versions are:http://arxiv.org/abs/physics/9904016 and http://pages.swcp.com/~jmw-mcw/binary_mole.htm.

User:SciMann (talk) Feb 6,2010

Wikipedia is not the place to promote new ideas that have not yet been covered in reliable sources. An unreviewed Arxiv paper has to be seen as a self-published source. The Joel Williams book appears to be issued by AuthorHouse, a self-publisher. EdJohnston (talk) 07:16, 7 February 2011 (UTC)

The Binary Mole definition is included in the first paragraph on the article page: "The constant happens to be quite close to an integer power of two, specifically only about 0.37% less than 2⁷⁹ mol−1, making the latter a useful approximation in nuclear physics when considering chain reaction growth rates. ^{citation needed}". I did not put it there. Obviously someone else thought it pertinent to the subject matter. As for a reference, the origin of this definition was set forth in this "Talk" section. It has also been presented by me in several other locations: "Changes in Avogadro's Number with Time (vixra;General Science Journal) and Avogadro's Number Needs A Simple Expression. Presumably, one of these is a proper reference for the statement.--SciMann (talk) 18:31, 21 December 2014 (UTC)

References