Talk:Avogadro constant

message: Copied from Good Article? above: 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. 
I would be interested to help document the proposed changes in the SI system and update the article as they get implemented. The mole (unit) article talks about the redefinition of the kilogram, but the implications for the mole are not spelled out, so the motivation to include it was not clear to everyone. I personally am looking forward to a better word for the quantity "amount-of-substance", which is a mouthful ("chemical amount" is being discussed, and is already used in some textbooks - an improvement, but still not as compact as Stoffmenge).Theislikerice (talk) 19:56, 18 August 2010 (UTC)
replies: text: You can propose to call this physical property stuff then. Other than that we should be careful to not do original research WP:OR by interpreting what is going to come and go. Kbrose (talk) 21:10, 18 August 2010 (UTC)
replies: text: It doesn't really matter what it's called (and it would be a bit WP:FORUM to discuss it here). Nevertheless, the debate seems notable, and kilogram shows that a lot could be said about it.  For this article, the Avogadro constant seems likely to get a defined value in the near future, although the "near future" might be 2015 rather than 2011: 2011 is the earliest possible date, but the debate has been going on for several years now and so seems worthy of a neutral mention. As far as understand it, we can't talk about "consequences" yet, because there are still too many options open. Physchim62 (talk) 22:40, 18 August 2010 (UTC)
replies: text: The redefinition of "mole" as a fixed exact number of particles has happened. The article has been partly updated accordingly. --Jorge Stolfi (talk) 02:23, 1 June 2019 (UTC)
thread_title:  Plans for setting the Avogadro constant to a fixed, exact value 

message: To the main editors of this article:
Please follow this link from Physikalisch-Technische Bundesanstalt (PTB), 2011-01-27:
The "new" kilogram is approaching
Here is the abstract and citation:
A milestone in the international Avogadro project coordinated by the Physikalisch-Technische Bundesanstalt (PTB) has been reached: With the aid of a single crystal of highly enriched 28Si, the Avogadro constant has now been measured as exactly as never before with a relative overall uncertainty of 3 · 10-8. Within the scope of the redefinition of the kilogram, the value NA = 6.02214078(18) · 1023 mol-1 permits the currently most exact realization of this unit. The results have been published in the most recent edition of the journal "Physical Review Letters".
Andreas, B.; Azuma, Y.; Bartl, G.; Becker, P.; Bettin, H.; Borys, M.; Busch, I.; Gray, M. et al. (2011), "An accurate determination of the Avogadro constant by counting the atoms in a 28Si crystal", Phys. Rev. Lett. 106 (3): 030801 (4 pages), doi:10.1103/PhysRevLett.106.030801.
Pmronchi (talk) 01:31, 10 February 2011 (UTC)
replies: text: Interesting. I haven't read the article, but just noticed that the accuracy was improved only by a factor of 18/30. Materialscientist (talk) 01:38, 10 February 2011 (UTC)
replies: text: Another interesting comment. Materialscientist (talk) 03:34, 10 February 2011 (UTC)
replies: text: Materialscientist, please post your reasons for the deletion from the article. SpinningSpark 07:10, 10 February 2011 (UTC)
replies: text: No hard feelings, potentially interesting material, but: (i) copy/paste from the quoted source; (ii) claims of an extraordinary achievement, whereas the accuracy was improved by less than 50% only, and at least another 50% is needed to reach the goal of "better kilogram standard" (i.e. work in progress); (iii) even though this was published in a respectable journal (Phys. Rev. Lett.), such strong-claim results are to be evaluated by international committees. Materialscientist (talk) 07:23, 10 February 2011 (UTC)

text: I've read through the article and it is odd, i.e. I don't understand the novelty claim: same accuracy was reported by NIST in 2007, but the difference in the NA values is beyond that accuracy. Materialscientist (talk) 08:16, 10 February 2011 (UTC)
replies: text: With the 2019 redefinition of mole and Avogadro number, these measurements now become measurements of the value of the dalton in relation to the kilogram.  The section on experimental measurements should perhaps be moved to atomic mass unit. --Jorge Stolfi (talk) 02:26, 1 June 2019 (UTC)
thread_title:  New value determined for the Avogadro constant (2011-01-27) 

message: To the main editors of this article (and other articles regarding constants)
Even though I´m not sure that this is the right place to raise this topic, I believe that constants whose precise value is still being determined, should not have too many digits of precision represented in articles different from the main article that deals with the constant. For instance, in the case of th Avogadro constant, as of today, it is represented in Amedeo Avogadro as being , which is not so anymore. If it were quoted as "being approximately ", for instance, that article would be correct no matter future, more precise definitions. The full precision value would be modified and found only in Avogadro constant, this article.
Pmronchi (talk) 01:36, 10 February 2011 (UTC)
replies: text: The correct way forward is to raise it on the talk page of the article(s) concerned, or else to edit the article directly yourself. There is nothing that can be done on this article to influence other articles. SpinningSpark 18:09, 10 February 2011 (UTC)
replies: text: With the 2019 redefinition of mole, this point is now moot.  But the observation may stil apply to atomic mass unit. --Jorge Stolfi (talk) 02:28, 1 June 2019 (UTC)
thread_title:  Referencing, in Wikipedia, the value of constants whose precise value is still being determined  

message: Following the link in the article, I get the new value 6.022 141 29(27) x 1023 mol-1. Perhaps an update is needed. -- 202.124.75.11 (talk) 13:41, 10 October 2011 (UTC)
replies: text: Updated. Thanks. Materialscientist (talk) 06:25, 11 October 2011 (UTC)
replies: text:  The article would be much clearer if all the other values are better identified as 'non-official' or estimates or calculated values or whatever they are that makes them not official. It is confusing to see these multiple values, especially when it is not clear why one is 'right.' Also, I expect most people do not understand the notation being used in expressing the number. What does the digits in parenthases mean? Where can a reader go to find out? 69.174.87.100 (talk) 22:33, 23 May 2012 (UTC)
replies: text: Since "amount of substance" now means effectively "number of particles", and "mole" is now just a fixed number of particles, the "Avogadro constant" is now a pure number.One could write "rad" or "deg" after a number as if they were "units of angle", but "1.57 rad" or "60 deg" are pure numbers for dimensional analysis; and the conversion factor can be written as "180/π deg/rad", but it is also a pure number.--Jorge Stolfi (talk) 02:37, 1 June 2019 (UTC)
replies: text: Even though mole is now effectively a dimensionless number, like the number of degrees per turn, the 9th BIPM retains the old dimensional analysis where "amount of substance" is considered a physical quantity while number or particles is a dimensionless number.  Thus, bureaucratically, the Avogadro constant still has dimension mol-1 while the Avogadro number is dimesnionless. Oh well.--Jorge Stolfi (talk) 16:39, 9 August 2023 (UTC)
thread_title:  New value 

message: The last paragraph of the history section has me skeptical:
:While it is rare to use units of amount of substance other than the mole, the Avogadro constant can also be defined in units such as the pound mole (lb-mol) and the ounce mole (oz-mol).
::N =  = 
Based on what is written, the article appears to be defining the Avogadro constant in terms of pounds per mole and ounce per mole.  I'm not a chemist, but I think someone should take a look at that and consider editing.
Thelema418 (talk) 06:09, 16 June 2012 (UTC)
replies: text: Agreed. The unit for the Avogadro constant is mol−1. It is independent of mass, hence using units lb-mol−1 and oz-mol−1 (or kg-mol−1) is nonsense.  — Preceding unsigned comment added by 92.13.20.6 (talk) 16:58, 19 July 2012 (UTC)
replies: text: (lb-mol) is not a pound times a mole, but rather an amount of substance containing the same number of entities as 12 lbs of carbon atoms. It's an obscure unit, but has the same dimensions as mole. So the article is correct, but confusing because it mentions a unit that is hardly ever used. --Theislikerice (talk) 03:59, 3 August 2012 (UTC)
replies: text: Seems resolved now. --Jorge Stolfi (talk) 02:59, 1 June 2019 (UTC)

text:  No, the defiinition of mole has changed radically in 2019.  Now one mole means exactly 6.022'140'76 × 1023 particles; which is close, but not equal, to the number of atoms in 12 grams of 12C.--Jorge Stolfi (talk) 16:47, 9 August 2023 (UTC)
thread_title:  Units in Article: Error? 

message: In the current(1971) definition of a mole, Avagadro's number is the number of atoms in 12 grams of carbon ( C12 ).
Thus in this definition, the number has units of g-1.  The inverse of Avagadro's number is approximately the mass of a neutron in grams. If Avagadro's number were dimensionless there would be no need for lb-mol, and oz-mol.
If this number were fixed by definition AND the existing definition were retained, then Avagadros number would effectively define the kilogram in terms of the mass of an atom of carbon-12.
But this is not the proposal, the proposal is to give a fixed value to Avagadro's number and change the definition of a mole such that the mass of an atom of carbon-12 is to be determined by experiment. If this definition is adopted then Avagadro's number becomes dimensionless and so does a mole. As follows:
* Proposal
The mole is the unit of amount of substance of a specified elementary entity, which may be an atom, molecule, ion, electron, any other particle or a specified group of such particles; its magnitude is set by fixing the numerical value of the Avogadro constant to be equal to exactly 6.02214X ×1023 when it is expressed in the unit mol-1.
(where X is a digit yet to be agreed upon).
Martin Milton(NPL)-A new definition for the mole based on the Avogadro constant; a journey from physics to chemistry, 7 April 2014
http://www.ucl.ac.uk/~ucahhwi/LTCC/section3-dimensional.pdf
In other words, under the new definition a mole, becomes 6.022 14X ×1023 particles and is not linked to any particular mass.
Davidcroquet (talk) 11:08, 7 April 2014 (UTC)
replies: text: I thought it was called Avogadro's Number not 'Constant'. As I understand it, the units are grams per mole [g/mol].  — Preceding unsigned comment added by 81.99.111.179 (talk) 16:13, 21 May 2014 (UTC)
replies: text: The unit of the Avogadro constant is not g−1. If the defintion of NA was "the number of atoms in 12 grams of carbon", then NA would be an adimensional number.However most people seem to understand it as "the constant that, multiplied by the amount of substance in a sample, gives the number of particles of that substance in that sample". Thus one must consider how "amount of substance" is defined. Here is what I understand from the IBPM deliberations:Between 1971 and 2019, in the SI, "amount of substance" was a separate dimension of measurement, like length or time, and the mole was a unit of that quantity.  Thus the Avogadro constant had the dimension of reciprocal of amount of substance, and it was about 6.02×1023 mol−1, which was to be determined experimentally.After 2019-05-20, in the SI, "amount of substance" is essentially "number of particles", and "2.5 moles of X" means "exactly 2.5 × 6.02214076×1023 particles of X".  Thus the amount of substance in a sample is a pure number (of particles), and the Avogadro constant too is now the pure number 6.02214076×1023 ("the number of particles in 6.02214076×1023 particles"); even though it can still be written as 6.02214076×1023 mol−1 or 6.02214076×1023 particles/mol.--Jorge Stolfi (talk) 03:23, 1 June 2019 (UTC)
thread_title:  Units of Avagadro's constant/number 

message: I found interesting way for demonstrating NA by factorial & only  with 2,3
it may be exact value of NA in future!!!غلامعلي نوري (talk) 06:17, 14 August 2015 (UTC)
thread_title: Something interesting 

message: :The units for this constant (or "number") for some is kg/kmol, not just g/mol, as specifically mentioned in many physics textbooks. In chemistry due to small laboratory measurements it is g/mol. I changed it to kg * mol^-1 to clarify this.  Dandtiks69 (talk) 02:11, 20 May 2015 (UTC)
replies: text: No, the unit of the Avogadro constant is "particles per mol", not "g/mol" or "kg/mol".  Before 2019 "mol" whas the unit of "amount of substance" which was a separate measurement dimension like length or time. Now it is just a number of particles, so the constant is a pure number. --Jorge Stolfi (talk) 03:28, 1 June 2019 (UTC)
thread_title: Wrong unit?

message: Why do scientists care about this number? That's unclear. I get that it's part of (most of, really) the definition of how many atoms in a mole, but what is unclear is why they didn't simply set one mole to equal 10^24 and be done with it  — Preceding unsigned comment added by 64.121.6.113 (talk) 16:16, 10 November 2015 (UTC)
replies: text: Explained now, hopefully.  Makes "mass of one mole in grams" equal to "mass of one molecule in daltons". --Jorge Stolfi (talk) 03:32, 1 June 2019 (UTC)
thread_title:  Significance needs to be better explained 

message: It needs to be more clearly explained that Avogadro's Number is also the number of daltons (atomic mass units) in a gram. Without that piece of information the mole seems like an absurd arbitrary unit.
::Done already --Jorge Stolfi (talk) 03:33, 1 June 2019 (UTC)
thread_title:  Daltons per Gram 

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thread_title:  External links modified 

message: ((((376.730313/299792458) (m^2)) / (pi s)) / (6.03676081927e+23 * ((mol / 1000)^(-1)))) / Planck's constant = 1 mol / kg
1.38064852e-23 * 6.03676081927e+23 = 8.33464489072
((2.176470e-8 kg) * ((1.616229e-35 m)^2)) / ((1.416808e+32 K) * ((5.39116e-44 s)^2) * (1 gram)) = 1.38064821e-23 Boltzmann
((2.176470e-8 kg) * ((1.616229e-35 m)^2)) / ((1.416808e+32 K) * ((5.39116e-44 s)^2)) = 1.38064821e-26 Boltzmann / 1000
Mol is per Gram  = (Mol * 1000) per kilogram
Mol should be Adjusted to units of Kilograms for Clarity  
 
(6.03676081927e+23 Avogadro) , (Gas Constant 8.33464489072) , (Boltzmann's Constant) , (Mole)
((((376.730313/299792458) (m^2)) / (pi s)) / (6.03676081927e+23 * ((mol / 1000)^(-1)))) / Planck's constant = 1 mol / kg
1.38064852e-23 * 6.03676081927e+23 = 8.33464489072
((2.176470e-8 kg) * ((1.616229e-35 m)^2)) / ((1.416808e+32 K) * ((5.39116e-44 s)^2) * (1 gram)) = 1.38064821e-23 Boltzmann
((2.176470e-8 kg) * ((1.616229e-35 m)^2)) / ((1.416808e+32 K) * ((5.39116e-44 s)^2)) = 1.38064821e-23  = Boltzmann per kilogram 
Mol is per Gram = (Mol * 1000) per kilogram
(Moles, Gas Constant & Avogadro Constant) should be Adjusted to (Units of Kilograms & Boltzmann's Constant) for Clarity
1.38064821e-23 * 6.03676081927e+26 = 8334.64301932
0.25 / 0.0000299792458 = 8339.10237995
1 / (4.00e-13 * 3e+8) = 8333.33333333
https://en.wikipedia.org/wiki/Mole_(unit)
The number of molecules per mole is known as Avogadro's constant, and is defined such that the mass of one mole of a substance, ((expressed in grams)), is equal to the mean relative molecular mass of the substance.
((2.176470e-8 kg *(1.616229e-35 m)^2/(1.416808e+32 K *((5.39116e-44 s)^2) =(1.38064852e-23 m^2 kg s^-2 K^-1) 
https://en.wikipedia.org/wiki/Boltzmann_constant 
(1 / ((c^3) * ((1.616229e-35 meters) / (pi / (((1 / (2 * pi)) + 1)^0.5))) * ((5.39116e-44 seconds) / (pi / (((1 / (2 * pi)) + 1)^0.5)))))^0.5 = 6.02220471e+26 
https://en.wikipedia.org/wiki/Avogadro_constant 
((1 / ((c^3) * ((1.616229e-35 meters) / (pi / (((1 / (2 * pi)) + 1)^0.5))) * ((5.39116e-44 seconds) / (pi / (((1 / (2 * pi)) + 1)^0.5)))))^0.5) * 1.38064852e-23 = 8314.54802 
https://en.wikipedia.org/wiki/Gas_constant
pi / (1 / (2pi) + 1) = 2.71024393443899972
Fuller.david (talk) 16:34, 25 September 2017 (UTC)
thread_title:  (6.03676081927e+23  Avogadro)  , (Gas Constant   8.33464489072) 

message: It seems that now the SI definition of mole is "an amount of substance that contains NA particles", where NA is the Avogadro constant.  Therefore NA is a fixed pure number 6.02...×1023, not a "number of particles per mole", (since the latter would make the definition of mole circular). No? --Jorge Stolfi (talk) 06:41, 18 May 2019 (UTC)
replies: text: No, otherwise formulas like n = N/N_A wouldn't work. But see the IUPAC press release: "The mole [...]. This number is the fixed numerical value of the Avogadro constant, N_A, when expressed in mol−1, and is called the Avogadro number." Christian75 (talk) 09:29, 18 May 2019 (UTC)
replies: text: The thing is confusing since the number of moles is itself dimensionally a pure number.  "One mole" is totally like "one dozen" or "one million".  Think of "two moles of H2" as "two dozen H2s"  Amounts in moles or in number of molecules are like angles in degrees or in radians. The formula n = N/N_A is similar to ang_degrees = (180/π) × ang_radians.  The constant 180/π can be said to have units of "degrees per radian", but since both are adimensional, it is a pure number too.  Or the conversion between inches and mm by the formula "length_mm = 25.4 × length_inches".  The constant "25.4" can be said to have units "mm/inch", but that is at best a mnemonic, because dimensionally it is a pure number too.There seems to be a popular perception that "amount of substance" is a physical quantity  like "mass", and thus "mole" has a physical dimension like "kg".  That is not what I read in the IUPAC, although their language is rather convoluted -- perhaps to bow to this popular feeling?--Jorge Stolfi (talk) 04:01, 20 May 2019 (UTC)
replies: text: OK, now I see that, in the SI, "amount of substance" was an independent dimension of measurement between 1971 and 2019.  Then NA had the dimension "reciprocal of amount of substance" and (non-trivial) unit mol−1.  But since 2019, "amount of substance" is just "number of particles",  the mole is a fixed number NA of particles, and NA is therefore a pure number ("particles per 6.02214076×1023 particles") even though one may still write "NA = 6.02214076×1023 mol−1" or "NA = 6.02214076×1023 particles/mol". --Jorge Stolfi (talk) 03:42, 1 June 2019 (UTC)
thread_title:  Article head is now incorrect? 

message: Now that the value of NA is defined to be a fixed integer, the section "Measurements" is no longer about determining NA, but instead about determining the value of the dalton in grams; that is, the number of atoms in 12 g (exactly) of carbon-12 (which is no longer equal to 1 mol of carbon-12).Therefore I propose moving that section to atomic mass unit, with the appropriate changes.--Jorge Stolfi (talk) 03:53, 1 June 2019 (UTC)
thread_title:  Move section "Measurement' to [[atomic mass unit]] 

message: Einstein used Brownian motion to estimate Avagadro's number in 1905? If my history is correct, and it might not off a little, he obtained it as the ratio of the ideal gas constant, usually denoted by "R", to Boltzmann's constant which is usually denoted by k or k_B: N_A = R/k_B. I saw the Scientific American piece (by Bodin, I think) who wrote as if Perrin was the first modern estimate of N_A and was puzzled by his neglect of Einstein on this issue. I guess I can add something but I'd have to dig up the original reference.  Ok. I found the original reference to Einstein's Brownian motion paper. The final equation in the 1905 "miracle year" paper gives Avagadro's number in terms off the time and displacement of spherical random walkers: N = t/lambda_x^2 RT/(3 pi kP). Here lambda_x^2 is the mean (square) displacement of the random walkers, t is the time they walked for, R and T and the ideal gas constant and absolute temperature, k is the coefficient of friction of the liquid, and P is the radius of the spherical walkers. To my mind this ought to appear pretty high in the article. Smoluchowski also solved the Brownian motion problem in 1906 and my understanding is that his work was independent of Einstein's. I haven't read Smoluchowski though, so I don't know whether he too derived an experimental formula for Avagadro's number. Further my understanding is that in these years you couldn't shake a stick without running into Avagadro's number and it was its appearance in so many places all giving similar experimental values that ultimately vanquished the anti-atomists. I think something along these lines is in Pais' Einstein biography "Subtle is the Lord." 
Additionally, his doctoral thesis, "A New Determination of Molecular Dimensions” contains an estimate of Avagadro's number which came in at about 2 x 10^23. 
— Preceding unsigned comment added by 76.113.29.12 (talk) 13:49, 3 June 2019 (UTC)
thread_title:  Why is Einstein not mentioned? 

message: "[...] replaces the earlier concept of an experimentally-determined, dimensionless, Avogadro number."  Not really accurate: it has not been replaced, and it is no longer experimentally determined, even though it was previously.  The 2019 redefinition provides a definition of the Avogadro number, and the lead should IMO reflect the modern position, with history in an appropriate section.  The New SI defines both the Avogadro constant () and the Avogadro number (with no symbol being provided by the definition, but here I'll use ) in such a way that .  —Quondum 16:32, 6 June 2019 (UTC)
replies: text: Ad I tried to explain in the previous section, the definitions in the 9th brochure now say that the "mole" is a specific count of particles (like "dozen particles" or "billion particles"), that the units "mol" and "mol" are adimensional (like "rad" and "rad"; and therefore the "Avogadro constant" is now adimensional, and the same as the Avogadro number — in spite of what the accompanying discussions in the brochure suggest. --Jorge Stolfi (talk) 19:42, 10 June 2019 (UTC)
replies: text: I've simplified the intro to skate over this technical distinction for the time being, until we have consensus about what position the article should take on this. -- The Anome (talk) 18:56, 12 June 2019 (UTC)
replies: text: My original point in this thread was unrelated to the technicalities being discussed in the thread above.  My point was that there is a new definition of the Avogadro number that is not experimentally determined, and that we should state this in the lead.  This is not replaced by the Avogadro constant; the new definition of the Avogadro constant uses this definition of the Avogadro number.  —Quondum 20:14, 12 June 2019 (UTC)

text: I propose "The Avogadro number is defined to be the dimensionless value .  The Avogadro constant is defined in terms of the Avogadro number." to replace "The exactly defined Avogadro constant replaces the earlier concept of an experimentally-determined Avogadro number that emerges from some other definition of the mole." in the lead.  This is a reasonably accurate reflection of the definition in the recent 9th SI brochure: "The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly  elementary entities. This number is the fixed numerical value of the Avogadro constant, N, when expressed in the unit mol and is called the Avogadro number."  —Quondum 23:02, 14 June 2019 (UTC)
thread_title:  Avogadro number in the New SI 

message: I propose to move the whole "Measurements" section to the atomic mass unit article, with the appropriate adaptations and ordering.  (Note that there is already a separate proposal to merge atomic mass constant into that article as well.)The justification for this move is that, given the new SI definitions of the mole and of the Avogadro constant, those experiments have become irrelevant to these concepts. The Avogadro number no longer needs (or can) be measured experimentally.On the other hand, those experiment now can and must be viewed as being aimed to determine the mass (in grams) of whatever reference particle was/is used to define the dalton; and, as such, they continue to have the same current or historical interest that they had until the redefinition.Thoughts? --Jorge Stolfi (talk) 03:58, 4 July 2019 (UTC)
replies: text: There is quite a bit in this article that needs this sort of rewrite.  Keep in mind, though, that some version of this might still belong in the 'History' section.  —Quondum 22:35, 5 July 2019 (UTC)
replies: text:  I moved the section as announced above.  I agree that some of that material should be restored to the history section, but probably in an abridged form; the reader who needs more information should be directed to atomic mass unit.  Makes sense?I will try to do that later this week (drained my batteries for today...)All the best, --Jorge Stolfi (talk) 05:10, 9 July 2019 (UTC)
replies: text: Definitely.  —Quondum 12:06, 9 July 2019 (UTC)
thread_title:  Proposal to move the "Measurement" section to [[atomic mass unit]]/[[atomic mass constant]] 

message: "universal atomic mass unit" appears instead of "unified atomic mass unit" at least two times.
18/6.021 appears instead of 18/6.022
pietro151.29.1.146 (talk) 18:52, 9 February 2020 (UTC)
thread_title:  misprints 

message: I think an interesting + useful addition to this article would be a discussion of when students/researchers are likely to encounter the constant in any practical setting.   I.e., aside from the definitional value and knowing the concept, is the Avogadro constant ever frequently used in any context during calculations, experiments, or other purposes?  Supernova87a (talk) 20:42, 13 March 2021 (UTC)
thread_title:  Practical usage? 

message: I think there should be a section outlining some of the methods that have been used to determine the Avogadro constant, particularly the early ones. The article mentions Perrin and Loschmidt as having done it (or something equivalent) but the articles on those people don't describe how they did it either.
I emphasised the historical methods above, because discovering how much atoms/molecules weigh is a monumental step in our understanding of matter, so it would be good to see how that step was achieved.
As I came to the article in search of information on this topic, I am, necessarily, unqualified to write on it myself!  Macboff (talk) 09:08, 6 August 2021 (UTC)
thread_title:  Methods of determining the Avogadro constant 

message: Avogadro's number 2400:ADCC:10C:8800:C844:27EE:7DFF:B9B2 (talk) 05:03, 17 May 2022 (UTC)
thread_title:  Chemistry 

message: I often wonder why it is not more well known that Avogadro's number is close to 2^79 (it's off by less than 0.4 %).
It means that if you take an amount of a substance equal to 1 mole, you can in principle halve it 79 times; then you are left with just one molecule. (Also, if you have an amount of matter somewhere between a grain of sand and a bus, you can halve it between roughly 70 and 100 times - except neither is of course made up of one kind of molecule only.)
I think it is a brilliant way to illustrate the scale of Avogadro's number, and the graininess of the material world.
But ... of course, to add it here, we'd need a source. Does anyone know of a valid source for this? Nø (talk) 14:04, 26 September 2022 (UTC)
replies: text: PS. It is also fairly close to 24!, but here the error is nearly 3%, and unlike the power-of-two, there is no obvious popular interpretation. I have found a few internet pages discussing one or the other of these two spurious facts, including posts claming that there is a movement to replace the official value of the Avogadro constant with 2^79. But I have found no pages that are valid sources - not even close! Nø (talk) 10:33, 23 February 2023 (UTC)
thread_title:  Two to the power of 79 

message: Fix this Nonsense. 2600:1004:B172:5DC5:5208:62FE:A94:3994 (talk) 12:15, 21 February 2023 (UTC)
replies: text: Visiting the article 15 minutes after this post, I don't see the problem. The article hasn't been revised for a copuple of weeks (unless the edit & reverse has been hidden). If you still se a problem, please explain more carefully. Nø (talk) 12:32, 21 February 2023 (UTC)
thread_title:  I don't know whodunnit, but as of right now, y Article on Avagadro's number constant contains sheer nonsense, substituting y word approximate for y word exact, and y word nucleons for y words particles or molecules. It is now '023 Feb 21 Tues 07:06EST. I am RA Fritz Skees, of NC State University school of Electrical Engineering, A1FritzYeCat@Yahoo.com, 8282796535 cel'phone. This nonsens must be fixed. 

message: It is now 2023-05-21. I agree with RA Fritz Skees who pointed this out on  23rd Feb 2021. The definition is a messy contradiction, and it needs rewritten. Someone knowledgeable please rewrite, and distinctly separate history from definition. EdwinaTS (talk) 06:02, 21 May 2023 (UTC)
thread_title:  A load of nonsense 

message: The article currently notes 
The electric charge per mole of electrons is a constant called the Faraday constant and has been known since 1834, when Michael Faraday published his works on electrolysis. 
The work of Faraday was based on mass of a substance having no relation to Na, i.e. the notion of a specific number of particles per mole.  The Faraday Constant as related to the mole was named in his honor some time later after Avogadro's number was established.  The fundamental origin of the value associated with Avogadros number was the Boltzmann constant Kb which was originally assigned by Max Plank. Na = R/Kb Zxooom (talk) 22:29, 31 May 2023 (UTC)
thread_title:  First Measurements 

message: Since  reverted my edit, I'd like to bring "Avogadro" vs "Avogadro's" number to discussion.
Firstly, "Avogadro's" seems to be in much higher use, as even when you restrict the search to be "Avogadro number", the vast majority of sources use the possessive form, and a wide array of reliable sources spell it as such.
Quondum's main point was citing: Bureau International des Poids et Mesures (2019): The International System of Units (SI), 9th edition, English version. And they do call it the "Avogadro number". But does it really outweigh all the others? I know it is kind of the one authoritative source on this, but at least both should be listed in my opinion. BhamBoi (talk) 21:57, 11 June 2023 (UTC)
replies: text: Google hit counts are pretty meaningless, Google's algorithm clearly does not use the "restriction" the way you intend it, and you seem to think that majority occurrence across the web carries weight on WP for technical terminology.  The term "Avogadro's number" also is often used to mean the Avogadro constant, so you'd have to figure out how to filter by meaning.  Ideally, we need reliable sources that discuss the terminology.  You have unfortunately not provided anything that can be worked from.  —Quondum 23:34, 11 June 2023 (UTC)
thread_title:  "Avogadro number" vs. "Avogadro's number" 

message: Would someone talk about why some places on the web show the 
Avogadro constant or number is:
6.02252×10^23
but Wikipedia cites it as:
6.02214076×10^23
Those two are not the same number.
Confer #1 & #2 below, 
with #3 Wikipedia. 
(#1):
https://www.infoplease.com/encyclopedia/science/chemistry/concepts/avogadros-number
Avogadro's number ... is equal to ...  6.02252×10^23.
(#2):
https://www.encyclopedia.com/science-and-technology/chemistry/chemistry-general/avogadros-number
Avogadro constant (Avogadro number) The number of molecules, atoms, or ions in one mole of a substance: 6.02252 × 10^23 per mol. 
(#3): Wikipedia 
The Avogadro constant ... 
with an exact value of 
6.02214076×1023 Jrodor (talk) 09:04, 31 May 2024 (UTC)
replies: text: Those are probably old values with larger uncertainty than what the last experimentally determined value had. See the table of old values at https://chemistry.stackexchange.com/a/144406 Jähmefyysikko (talk) 15:21, 31 May 2024 (UTC)
replies: text: Thank-you for the URL to that table of historical values!  That is exactly what I was looking for, but couldn't find on my own.  Perfect response! Jrodor (talk) 05:44, 1 June 2024 (UTC)
thread_title:  Different values 6.02252 vs  6.02214076?