Difference between revisions of "Unified atomic mass unit"

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== [[Orange Book]] Entry ==
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{{Final
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|acronym=, ''u''
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|def='''unified atomic mass unit''', ''u''
  
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'''[[Dalton]]'''
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Non-SI unit of mass defined as one-twelfth of the mass of one atom of <sup>12<<sup>-27</sup> kg where the digits in parentheses indicate the estimated uncertainty in the final two digits of the value. Equivalent to the dalton (Da) unit.
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:''Note'': The abbreviation [[amu]] for [[atomic mass unit]] is deprecated; it has been used to denote atomic masses measured relative to a single atom of <sup>16</sup>O, or to the isotope-averaged mass of an oxygen atom, or to a single atom of <sup>12</sup>C.
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|rel=
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|ref={{gb}}
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P. J. Mohr, B. N. Taylor, D. B. Newell. Rev. Mod. Phys. 84, 1527 (2012). (http://dx.doi.org/10.1103/RevModPhys.84.1527 )
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}}
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<!-- Orange Book -->
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{{orange|
 
This unit  (u) is based on the standard that the mass of <sup>12</sup>C is exactly 12 u. The older symbol, [[amu]], using the standard based on the mass of <sup>16</sup>O is no longer recommended. In biochemistry the term [[dalton]], symbol [[Da]], is sometimes used but is not here recommended.
 
This unit  (u) is based on the standard that the mass of <sup>12</sup>C is exactly 12 u. The older symbol, [[amu]], using the standard based on the mass of <sup>16</sup>O is no longer recommended. In biochemistry the term [[dalton]], symbol [[Da]], is sometimes used but is not here recommended.
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}}
  
== [[Gold Book]] Entry ==
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<!-- Gold Book -->
 
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{{gold|
 
'''unified atomic mass unit'''
 
'''unified atomic mass unit'''
  
Non-SI unit of mass (equal to the atomic mass constant), defined as one
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Non-SI unit of mass (equal to the atomic mass constant), defined as one twelfth of the mass of a carbon-12 atom in its ground state and used to express masses of atomic particles, u &61; 1.660 5402(10) x 10<sup>-27</sup> kg.
twelfth of the mass of a carbon-12 atom in its ground state and used to
 
express masses of atomic particles, u = 1.660 5402(10) x 10<sup></sup> kg.
 
  
 
[http://www.iupac.org/goldbook/U06554.pdf IUPAC]
 
[http://www.iupac.org/goldbook/U06554.pdf IUPAC]
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}}
  
== Proposed New Entry ==
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== See also ==
 
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*[[Mass]]
Non-SI [[Wikipedia:physical unit|unit]] of mass, defined as 1/12 of the mass of the carbon-12 atom in its ground state.
 
The '''unified atomic mass unit''' has the symbol '''u''' and is not widely used in mass spectrometry, partly because of the clumsy name "unified atomic mass unit" which gets even worse when used with a [[Wikipedia:SI prefix|SI prefix]], e.g. "kilo unified atomic mass unit".
 
Therefore it is recomendet to use the supplementary term [[Dalton]]. The Dalton is defined as
 
 
  
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== External links ==
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*[http://physics.nist.gov/cgi-bin/cuu/Value?ukg NIST 2002 CODATA]
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*[[Wikipedia:Atomic mass]]
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*[[Wikipedia:Atomic mass unit]]
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*[http://publications.iupac.org/ci/2004/2601/1_holden.html Atomic weights and the international committee–a historical review] Chemistry International 2004
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*H.E. Duckworth, A.O. Nier, "Evolution of the unified scale of atomic mass, 12C = 12u," ''Int. J. Mass. Spectrom. Ion Processes.'' '''86''' (1988) 1–19. doi:[http://doi.org/10.1016/0168-1176(88)80051-X 10.1016/0168-1176(88)80051-X].
  
== External Links ==
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[[Category:Mass]]
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[[Category:Units]]
  
[[Wikipedia:Atomic mass]]
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[[Category:General]]
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{{DEFAULTSORT:Unified Atomic Mass Unit}}
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[[Category:Orange Book term]]

Latest revision as of 17:09, 9 August 2019

IUPAC RECOMMENDATIONS 2013
Unified atomic mass unit , u
unified atomic mass unit, u

Dalton

Non-SI unit of mass defined as one-twelfth of the mass of one atom of 12<-27 kg where the digits in parentheses indicate the estimated uncertainty in the final two digits of the value. Equivalent to the dalton (Da) unit.

Note: The abbreviation amu for atomic mass unit is deprecated; it has been used to denote atomic masses measured relative to a single atom of 16O, or to the isotope-averaged mass of an oxygen atom, or to a single atom of 12C.
Related Term(s):
Reference(s):

IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins.

P. J. Mohr, B. N. Taylor, D. B. Newell. Rev. Mod. Phys. 84, 1527 (2012). (http://dx.doi.org/10.1103/RevModPhys.84.1527 )

From Definitions of Terms Relating to Mass Spectrometry (IUPAC Recommendations 2013); DOI: 10.1351/PAC-REC-06-04-06 © IUPAC 2013.

Index of Recommended Terms

 




Orange Book

ORANGE BOOK DEFINITION

IUPAC. Analytical Division. Compendium of Analytical Nomenclature (the Orange Book). Definitive Rules, 1979.

Unified atomic mass unit

This unit (u) is based on the standard that the mass of 12C is exactly 12 u. The older symbol, amu, using the standard based on the mass of 16O is no longer recommended. In biochemistry the term dalton, symbol Da, is sometimes used but is not here recommended.

IUPAC 1997 Orange Book Chapter 12
Index of Orange Book Terms


Gold Book

GOLD BOOK DEFINITION

IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997).

Unified atomic mass unit

unified atomic mass unit

Non-SI unit of mass (equal to the atomic mass constant), defined as one twelfth of the mass of a carbon-12 atom in its ground state and used to express masses of atomic particles, u &61; 1.660 5402(10) x 10-27 kg.

IUPAC

IUPAC Gold Book
Index of Gold Book Terms


See also

External links