Physics:Isotopes of magnesium
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| Standard atomic weight Ar, standard(Mg) |
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Magnesium (12Mg) naturally occurs as three stable isotopes: 24Mg, 25Mg, and 26Mg. There are also 19 artificial radioisotopes that have been discovered, ranging from 18Mg to 40Mg (with the exception of 39Mg). The longest-lived of them is 28Mg with a half-life of 20.915 hours. The isotopes lighter than the stable ones mostly decay to isotopes of sodium, while those heavier decay to isotopes of aluminium.
A precise measurement of the neutron-rich 40Mg in 2019 showed an unexpected difference in its nuclear structure, compared to the lighter neighboring isotopes.[2][3]
List of isotopes
| Nuclide |
Z | N | Isotopic mass (u) [n 1] |
Half-life [n 2] |
Decay mode [n 3] |
Daughter isotope [n 4] |
Spin and parity [n 5][n 2] |
Physics:Natural abundance (mole fraction) | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Normal proportion | Range of variation | |||||||||
| 18Mg[4] | 12 | 6 | 2021 | 4.0(3.4) zs | 2p | 16Ne[n 6] | 0+ | |||
| 19Mg | 12 | 7 | 19.034180(60) | 2007 | 5(3) ps | 2p | 17Ne | 1/2−# | ||
| 20Mg | 12 | 8 | 20.0187631(20) | 1974 | 90.4(5) ms | β+ (69.7(1.2)%) | 20Na | 0+ | ||
| β+p (30.3(1.2)%) | 19Ne | |||||||||
| 21Mg | 12 | 9 | 21.0117058(8) | 1965 | 120.0(4) ms | β+ (79.8(2.1)%) | 21Na | 5/2+ | ||
| β+p (20.1(2.1)%) | 20Ne | |||||||||
| β+α (0.116(18)%) | 17F | |||||||||
| β+pα (0.016(3)%) | 16O | |||||||||
| 22Mg | 12 | 10 | 21.99957060(17) | 1961 | 3.8745(7) s | β+ | 22Na | 0+ | ||
| 23Mg | 12 | 11 | 22.99412377(3) | 1939 | 11.3039(32) s | β+ | 23Na | 3/2+ | ||
| 24Mg | 12 | 12 | 23.985041689(14) | 1920 | Stable | 0+ | [0.7888, 0.7905] | |||
| 25Mg | 12 | 13 | 24.98583697(5) | 1920 | Stable | 5/2+ | [0.09988, 0.10034] | |||
| 26Mg[n 7] | 12 | 14 | 25.98259297(3) | 1920 | Stable | 0+ | [0.1096, 0.1109] | |||
| 27Mg | 12 | 15 | 26.98434065(5) | 1934 | 9.435(27) min | β− | 27Al | 1/2+ | ||
| 28Mg | 12 | 16 | 27.98387543(28) | 1953 | 20.915(9) h | β− | 28Al | 0+ | ||
| 29Mg | 12 | 17 | 28.9886072(4) | 1971 | 1.30(12) s | β− | 29Al | 3/2+ | ||
| 30Mg | 12 | 18 | 29.9904655(14) | 1971 | 317(4) ms | β− (> 99.94%) | 30Al | 0+ | ||
| β−n (< 0.06%) | 29Al | |||||||||
| 31Mg | 12 | 19 | 30.996648(3) | 1977 | 270(2) ms | β− (93.8(1.9)%) | 31Al | 1/2+ | ||
| β−n (6.2(1.9)%) | 30Al | |||||||||
| 32Mg | 12 | 20 | 31.999110(4) | 1977 | 80.4(4) ms | β− (94.5(5)%) | 32Al | 0+ | ||
| β−n (5.5(5)%) | 31Al | |||||||||
| 33Mg | 12 | 21 | 33.0053279(29) | 1979 | 92.0(1.2) ms | β− (86(2)%) | 33Al | 3/2− | ||
| β−n (14(2)%) | 32Al | |||||||||
| β−2n ? | 31Al ? | |||||||||
| 34Mg | 12 | 22 | 34.008935(7) | 1979 | 44.9(4) ms | β− (> 78.9(7.0)%) | 34Al | 0+ | ||
| β−n (21(7)%) | 33Al | |||||||||
| β−2n (< 0.1%) | 32Al | |||||||||
| 35Mg | 12 | 23 | 35.01679(29) | 1989 | 11.3(6) ms | β−n (52(46)%) | 34Al | (3/2−, 5/2−) | ||
| β− (48(46)%) | 35Al | |||||||||
| β−2n ? | 33Al ? | |||||||||
| 36Mg | 12 | 24 | 36.02188(74) | 1989 | 3.9(1.3) ms | β− (52(12)%) | 36Al | 0+ | ||
| β−n (48(12)%) | 35Al | |||||||||
| β−2n ? | 34Al ? | |||||||||
| 36mMg | 833 keV | 2024 | 90(+80-7) ms | IT | 36Mg | (0+) | ||||
| 37Mg | 12 | 25 | 37.03029(75) | 1996 | 8(4) ms | β− ? | 37Al ? | (3/2−) | ||
| β−n ? | 36Al ? | |||||||||
| β−2n ? | 35Al ? | |||||||||
| 38Mg | 12 | 26 | 38.03658(54)# | 2002 | 3.1(4 (stat), 2 (sys)) ms[5] | β−n (81%) | 37Al | 0+ | ||
| β− (9%) | 38Al | |||||||||
| β−2n (9%) | 36Al | |||||||||
| 40Mg | 12 | 28 | 40.05319(54)# | 2007 | 1# ms [> 170 ns] | β− ? | 40Al ? | 0+ | ||
| β−n ? | 39Al ? | |||||||||
| β−2n ? | 38Al ? | |||||||||
- ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- ↑ 2.0 2.1 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ↑
Modes of decay:
n: Neutron emission p: Proton emission - ↑ Bold symbol as daughter – Daughter product is stable.
- ↑ ( ) spin value – Indicates spin with weak assignment arguments.
- ↑ Also immediately emits two protons for the net reaction of 18Mg -> 14O + 4 1H
- ↑ Used in radiodating events early in the Solar System's history, as product of the extinct 26Al
See also
Daughter products other than magnesium
- Isotopes of aluminum
- Isotopes of sodium
- Isotopes of neon
- Isotopes of fluorine
- Isotopes of oxygen
References
- ↑ Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265–91. doi:10.1515/pac-2015-0305.
- ↑ Roberts, Glenn Jr. (2019-02-07). "New Measurements of Exotic Magnesium Suggest Surprising Shape-Shift" (in en-US). https://newscenter.lbl.gov/2019/02/07/new-measurements-exotic-magnesium-suggest-surprising-shape-shift/.
- ↑ "NP A Change in Structure for a Superheavy Magnesium Isotope" (in en-US). 2019-08-01. https://science.osti.gov/np/Highlights/2019/NP-2019-08-a.
- ↑ Jin, Y. (2021). "First observation of the four-proton unbound nucleus 18Mg". Physical Review Letters 127 (262502). doi:10.1103/PhysRevLett.127.262502. PMID 35029460.
- ↑ Crawford, H. L.Expression error: Unrecognized word "et". (2022). "Crossing N = 28 toward the neutron drip line: first measurement of half-lives at FRIB". Physical Review Letters 129 (212501). doi:10.1103/PhysRevLett.129.212501. PMID 36461950. Bibcode: 2022PhRvL.129u2501C.
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