Isotopes of potassium: Difference between revisions
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* Isotope masses from: |
* Isotope masses from: |
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**{{cite journal |
**{{cite journal|author=G. Audi |author2=A. H. Wapstra |author3=C. Thibault |author4=J. Blachot |author5=O. Bersillon |year=2003 |title=The NUBASE evaluation of nuclear and decay properties |url=http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf |journal=[[Nuclear Physics A]] |volume=729 |issue= |pages=3–128 |doi=10.1016/j.nuclphysa.2003.11.001 |bibcode=2003NuPhA.729....3A |deadurl=yes |archiveurl=https://web.archive.org/web/20080923135135/http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf |archivedate=2008-09-23 |df= }} |
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* Isotopic compositions and standard atomic masses from: |
* Isotopic compositions and standard atomic masses from: |
||
**{{cite journal |author=J. R. de Laeter |author2=J. K. Böhlke |author3=P. De Bièvre |author4=H. Hidaka |author5=H. S. Peiser |author6=K. J. R. Rosman |author7=P. D. P. Taylor |year=2003 |title=Atomic weights of the elements. Review 2000 (IUPAC Technical Report) |url=http://www.iupac.org/publications/pac/75/6/0683/pdf/ |journal=[[Pure and Applied Chemistry]] |volume=75 |issue=6 |pages=683–800 |doi=10.1351/pac200375060683}} |
**{{cite journal |author=J. R. de Laeter |author2=J. K. Böhlke |author3=P. De Bièvre |author4=H. Hidaka |author5=H. S. Peiser |author6=K. J. R. Rosman |author7=P. D. P. Taylor |year=2003 |title=Atomic weights of the elements. Review 2000 (IUPAC Technical Report) |url=http://www.iupac.org/publications/pac/75/6/0683/pdf/ |journal=[[Pure and Applied Chemistry]] |volume=75 |issue=6 |pages=683–800 |doi=10.1351/pac200375060683}} |
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**{{cite journal |author=M. E. Wieser |year=2006 |title=Atomic weights of the elements 2005 (IUPAC Technical Report) |url=http://iupac.org/publications/pac/78/11/2051/pdf/ |journal=[[Pure and Applied Chemistry]] |volume=78 |issue=11 |pages=2051–2066 |doi=10.1351/pac200678112051 |laysummary=http://old.iupac.org/news/archives/2005/atomic-weights_revised05.html}} |
**{{cite journal |author=M. E. Wieser |year=2006 |title=Atomic weights of the elements 2005 (IUPAC Technical Report) |url=http://iupac.org/publications/pac/78/11/2051/pdf/ |journal=[[Pure and Applied Chemistry]] |volume=78 |issue=11 |pages=2051–2066 |doi=10.1351/pac200678112051 |laysummary=http://old.iupac.org/news/archives/2005/atomic-weights_revised05.html}} |
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* Half-life, spin, and isomer data selected from the following sources. See editing notes on [[Talk:Isotopes of potassium|this article's talk page]]. |
* Half-life, spin, and isomer data selected from the following sources. See editing notes on [[Talk:Isotopes of potassium|this article's talk page]]. |
||
**{{cite journal |
**{{cite journal|author=G. Audi |author2=A. H. Wapstra |author3=C. Thibault |author4=J. Blachot |author5=O. Bersillon |year=2003 |title=The NUBASE evaluation of nuclear and decay properties |url=http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf |journal=[[Nuclear Physics A]] |volume=729 |issue= |pages=3–128 |doi=10.1016/j.nuclphysa.2003.11.001 |bibcode=2003NuPhA.729....3A |deadurl=yes |archiveurl=https://web.archive.org/web/20080923135135/http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf |archivedate=2008-09-23 |df= }} |
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**{{cite web |author=[[National Nuclear Data Center]] |year= |title=NuDat 2.1 database |url=http://www.nndc.bnl.gov/nudat2/ |publisher=[[Brookhaven National Laboratory]] |accessdate=23 February 2017}} |
**{{cite web |author=[[National Nuclear Data Center]] |year= |title=NuDat 2.1 database |url=http://www.nndc.bnl.gov/nudat2/ |publisher=[[Brookhaven National Laboratory]] |accessdate=23 February 2017}} |
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**{{cite book |author=N. E. Holden |year=2004 |editor=D. R. Lide |chapter=Table of the Isotopes |title=[[CRC Handbook of Chemistry and Physics]] |page=Section 11 |nopp=yes |edition=85th |publisher=[[CRC Press]] |isbn=978-0-8493-0485-9}} |
**{{cite book |author=N. E. Holden |year=2004 |editor=D. R. Lide |chapter=Table of the Isotopes |title=[[CRC Handbook of Chemistry and Physics]] |page=Section 11 |nopp=yes |edition=85th |publisher=[[CRC Press]] |isbn=978-0-8493-0485-9}} |
Revision as of 14:18, 15 April 2017
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Standard atomic weight Ar°(K) | ||||||||||||||||||||||||||||||
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Potassium (19K) has 24 known isotopes from 32K to 56K. Three isotopes occur naturally: stable 39K (93.3%) and 41K (6.7%), and the long-lived radioisotope 40K (0.012%).
Naturally occurring radioactive 40K decays to stable 40Ar (10.72% of decays) by electron capture or positron emission (giving it the longest known positron-emitter nuclide half-life). Alternately, and most of the time (89.28%), it decays to stable 40Ca by beta decay. 40K has a half-life of 1.248×109 years. The long half life of this primordial radioisotope is caused by a highly spin-forbidden transition: 40K has a nuclear spin of 4, while both of its decay daughters are even-even isotopes with spins of 0.
40K occurs in natural potassium (and thus in some commercial salt substitutes) in sufficient quantity that large bags of those substitutes can be used as a radioactive source for classroom demonstrations. In healthy animals and people, 40K represents the largest source of radioactivity, greater even than 14C. In a human body of 70 kg mass, about 4,400 nuclei of 40K decay per second.[3]
The decay of 40K to 40Ar enables a commonly used method for dating rocks. The conventional K-Ar dating method depends on the assumption that the rocks contained no argon at the time of formation and that all the subsequent radiogenic argon (i.e., 40Ar) was quantitatively retained. Minerals are dated by measurement of the concentration of potassium and the amount of radiogenic 40Ar that has accumulated.
All other potassium isotopes have half-lives under a day, most under a minute. The least stable are 33K and 34K, both with half-lives shorter than 25 nanoseconds. The half-life of 32K is unknown.
Outside of its use in dating 40K has been used extensively as tracers in studies of weathering. Various potassium isotopes also been used for nutrient cycling studies because potassium is a macronutrient required for life.
List of isotopes
nuclide symbol |
Z(p) | N(n) | isotopic mass (u) |
half-life | decay mode(s)[4] |
daughter isotope(s)[n 1] |
nuclear spin |
representative isotopic composition (mole fraction) |
---|---|---|---|---|---|---|---|---|
excitation energy | ||||||||
32K | 19 | 13 | 32.02192(54)# | unknown | p | 31Ar | 1+# | |
32mK | 950(100)# keV | unknown | 4+# | |||||
33K | 19 | 14 | 33.00726(21)# | <25 ns | p | 32Ar | (3/2+)# | |
34K | 19 | 15 | 33.99841(32)# | <25 ns | p | 33Ar | 1+# | |
35K | 19 | 16 | 34.988010(21) | 178(8) ms | β+ (99.63%) | 35Ar | 3/2+ | |
β+, p (.37%) | 34Cl | |||||||
36K | 19 | 17 | 35.981292(8) | 342(2) ms | β+ (99.94%) | 36Ar | 2+ | |
β+, p (.048%) | 35Cl | |||||||
β+, α (.012%) | 32S | |||||||
37K | 19 | 18 | 36.97337589(10) | 1.226(7) s | β+ | 37Ar | 3/2+ | |
38K | 19 | 19 | 37.9690812(5) | 7.636(18) min | β+ | 38Ar | 3+ | |
38m1K | 130.50(28) keV | 924.2(3) ms | 0+ | |||||
38m2K | 3458.0(2) keV | 21.98(11) µs | (7+),(5+) | |||||
39K | 19 | 20 | 38.96370668(20) | Stable | 3/2+ | 0.932581(44) | ||
40K[n 2][n 3] | 19 | 21 | 39.96399848(21) | 1.248(3)×109 y | β− (89.28%) | 40Ca | 4 | 1.17(1)×10−4 |
EC (10.72%) | 40Ar | |||||||
β+ (0.001%)[5] | ||||||||
40mK | 1643.639(11) keV | 336(12) ns | 0+ | |||||
41K | 19 | 22 | 40.96182576(21) | Stable | 3/2+ | 0.067302(44) | ||
42K | 19 | 23 | 41.96240281(24) | 12.360(12) h | β− | 42Ca | 2 | |
43K | 19 | 24 | 42.960716(10) | 22.3(1) h | β− | 43Ca | 3/2+ | |
44K | 19 | 25 | 43.96156(4) | 22.13(19) min | β− | 44Ca | 2− | |
45K | 19 | 26 | 44.960699(11) | 17.3(6) min | β− | 45Ca | 3/2+ | |
46K | 19 | 27 | 45.961977(17) | 105(10) s | β− | 46Ca | 2(−) | |
47K | 19 | 28 | 46.961678(9) | 17.50(24) s | β− | 47Ca | 1/2+ | |
48K | 19 | 29 | 47.965514(26) | 6.8(2) s | β− (98.86%) | 48Ca | (2−) | |
β−, n (1.14%) | 47Ca | |||||||
49K | 19 | 30 | 48.96745(8) | 1.26(5) s | β−, n (86%) | 48Ca | (3/2+) | |
β− (14%) | 49Ca | |||||||
50K | 19 | 31 | 49.97278(30) | 472(4) ms | β− (71%) | 50Ca | (0−,1,2−) | |
β−, n (29%) | 49Ca | |||||||
51K | 19 | 32 | 50.97638(54)# | 365(5) ms | β− (53%) | 51Ca | 3/2+# | |
β−, n (47%) | 50Ca | |||||||
52K | 19 | 33 | 51.98261(75)# | 105(5) ms | β−, n (64%) | 51Ca | (2−)# | |
β−, 2n (21%) | 50Ca | |||||||
β− (15%) | 52Ca | |||||||
53K | 19 | 34 | 52.98712(75)# | 30(5) ms | β−, n (67%) | 52Ca | (3/2+)# | |
β−, 2n (17%) | 51Ca | |||||||
β− (16%) | 53Ca | |||||||
54K | 19 | 35 | 53.99420(97)# | 10(5) ms | β− (>99.9%) | 54Ca | 2−# | |
β−, n (<.1%) | 53Ca | |||||||
55K | 19 | 36 | 54.99971(107)# | 3# ms | β− | 55Ca | 3/2+# | |
β−, n | 54Ca |
- ^ Bold for stable isotopes, bold italic for nearly-stable isotopes (half-life longer than the age of the universe)
- ^ Used in potassium-argon dating
- ^ Primordial radionuclide
Notes
- Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
- Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.
- Nuclide masses are given by IUPAP Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants (SUNAMCO).
- Isotope abundances are given by IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW).
References
- ^ "Standard Atomic Weights: Potassium". CIAAW. 1979.
- ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
- ^ "Radioactive Human Body". Retrieved 2011-05-18.
- ^ "Universal Nuclide Chart". nucleonica.
{{cite web}}
: Unknown parameter|registration=
ignored (|url-access=
suggested) (help) - ^ Engelkemeir, D. W.; Flynn, K. F.; Glendenin, L. E. (1962). "Positron Emission in the Decay of K40". Physical Review. 126 (5): 1818. Bibcode:1962PhRv..126.1818E. doi:10.1103/PhysRev.126.1818.
- Isotope masses from:
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
{{cite journal}}
: Unknown parameter|deadurl=
ignored (|url-status=
suggested) (help)
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
- Isotopic compositions and standard atomic masses from:
- J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
{{cite journal}}
: Unknown parameter|laysummary=
ignored (help)
- Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
{{cite journal}}
: Unknown parameter|deadurl=
ignored (|url-status=
suggested) (help) - National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved 23 February 2017.
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide (ed.). CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.
{{cite book}}
: Unknown parameter|nopp=
ignored (|no-pp=
suggested) (help)
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.