Editing Bohr magneton (section)

==History==
The idea of elementary magnets is due to [[Walther Ritz]] (1907) and [[Pierre Weiss]]. Already before the [[Rutherford model]] of atomic structure, several theorists commented that the magneton should involve the [[Planck constant]] ''h''.<ref name="Keith">{{cite book
 |first1=Stephen T. |last1=Keith |first2=Pierre |last2=Quédec
 |year=1992
 |chapter=Magnetism and Magnetic Materials: The Magneton
 |title=Out of the Crystal Maze
 |pages=384–394
 |isbn=978-0-19-505329-6
}}</ref> By postulating that the ratio of electron [[kinetic energy]] to orbital [[frequency]] should be equal to ''h'', [[Richard Gans]] computed a value that was twice as large as the Bohr magneton in September 1911.<ref name="Heilbron">{{cite journal
 |first1=John |last1=Heilbron 
 |first2=Thomas |last2=Kuhn
 |year=1969
 |title=The genesis of the Bohr atom
 |journal=[[Historical Studies in the Physical Sciences|Hist. Stud. Phys. Sci.]]
 |volume=1 |pages=vi–290 
 |doi=10.2307/27757291
 |jstor=27757291 
 |doi-access=free}}</ref> At the [[Solvay Conference#First Conference|First Solvay Conference]] in November that year, [[Paul Langevin]] obtained a value of <math>e\hbar/(2m_\mathrm{e})</math>.<ref>
{{cite conference
 |first=Paul |last=Langevin
 |author-link=Paul Langevin
 |year=1911
 |title=La théorie cinétique du magnétisme et les magnétons
 |trans-title=Kinetic theory of magnetism and magnetons
 |conference=La théorie du rayonnement et les quanta: Rapports et discussions de la réunion tenue à Bruxelles, du 30 octobre au 3 novembre 1911, sous les auspices de M. E. Solvay
 |conference-url=https://archive.org/details/lathoriedurayo00inst/page/404/mode/2up
 |page=404
}}</ref> Langevin assumed that the attractive force was inversely proportional to distance to the power <math>n+1,</math> and specifically <math>n=1.</math><ref>Note that the formula
<math display="block">I_o=\frac m{Me}\frac h{8\pi}\frac n{n+2}</math>
on page 404 should say
<math display="block">I_o=\frac {Me}m\frac h{8\pi}\frac n{n+2}.</math></ref>

The [[:Category:Romanian physicists|Romanian physicist]] [[Ștefan Procopiu]] had obtained the expression for the magnetic moment of the electron in 1913.<ref name = proc1>{{cite journal
 |first=Ștefan |last=Procopiu
 |year=1911–1913
 |title=Sur les éléments d'énergie |trans-title=On the elements of energy
 |journal=[[Annales scientifiques de l'Université de Jassy]]
 |volume=7 |page=280
}}</ref><ref name = proc2>{{cite journal
 |first=Ștefan |last=Procopiu
 |year=1913
 |title=Determining the Molecular Magnetic Moment by M. Planck's Quantum Theory
 |journal=[[Bulletin de la Section Scientifique de l'Académie Roumaine]]
 |volume=1 |pages=151
}}</ref>  The value is sometimes referred to as the "Bohr–Procopiu magneton" in Romanian scientific literature.<ref>{{cite web
 |title=Ștefan Procopiu (1890–1972)
 |url=http://www.etti.tuiasi.ro/sibm/old/Technical%20Museum/html/en/Stefan_Procopiu_en.htm
 |publisher=Ștefan Procopiu Science and Technology Museum
 |access-date=2010-11-03
 |archive-url=https://web.archive.org/web/20101118065825/http://www.etti.tuiasi.ro/sibm/old/Technical%20Museum/html/en/Stefan_Procopiu_en.htm
 |archive-date=2010-11-18
 |url-status=dead
 }}</ref> The [[Weiss magneton]] was experimentally derived in 1911 as a unit of [[magnetic moment]] equal to {{val|1.53|e=-24}} [[joule]]s per tesla, which is about 20% of the Bohr magneton.

In the summer of 1913, the values for the natural units of atomic angular momentum and magnetic moment were obtained by the Danish physicist [[Niels Bohr]] as a consequence of [[Bohr model|his atom model]].<ref name="Heilbron"/><ref>
{{cite book
 |first=Abraham |last=Pais
 |year=1991
 |title=Niels Bohr's Times, in physics, philosophy, and politics
 |publisher=[[Clarendon Press]]
 |isbn=0-19-852048-4
}}</ref>   In 1920, [[Wolfgang Pauli]] gave the Bohr magneton its name in an article where he contrasted it with the magneton of the experimentalists which he called the [[Weiss magneton]].<ref name="Keith"/>