Isotopes of magnesium

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Main isotopes of magnesium (12Mg)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
24Mg 79.0% stable
25Mg 10.0% stable
26Mg 11.0% stable
Standard atomic weight Ar, standard(Mg)[24.304, 24.307] conventional: 24.305[1][2]
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Magnesium (12Mg) naturally occurs in three stable isotopes, 24Mg, 25Mg, and 26Mg. There are 19 radioisotopes that have been discovered, ranging from 18Mg to 40Mg. The longest-lived radioisotope is 28Mg with a half-life of 20.915 hours. The lighter isotopes mostly decay to isotopes of sodium while the heavier isotopes decay to isotopes of aluminium. The shortest-lived is proton-unbound 19Mg with a half-life of 5 picoseconds, though the half-life of similarly unbound 18Mg has not been measured.

The abundances of the naturally occurring isotopes of magnesium.

List of isotopes[]

Nuclide[3]
 Z N Isotopic mass (Da)[4]
[n 1] 		Half-life
[n 2] 		Decay
mode
[n 3] 		Daughter
isotope
[n 4] 		Spin and
parity
[n 5][n 2] 		Natural abundance (mole fraction)
Normal proportion Range of variation
18Mg[5] 12 6 2p 16Ne 0+
19Mg 12 7 19.03417(5) 5(3) ps 2p 17Ne 1/2−#
20Mg 12 8 20.0187631(2) 93(5) ms β+ (69.7%) 20Na 0+
β+, p (30.3%) 19Ne
21Mg 12 9 21.0117058(8) 118.6(5) ms β+ (66.9%) 21Na 5/2+
β+, p (32.6%) 20Ne
β+, α (0.5%) 17F
22Mg 12 10 21.9995707(3) 3.8755(12) s β+ 22Na 0+
23Mg 12 11 22.99412394(17) 11.317(11) s β+ 23Na 3/2+
24Mg 12 12 23.985041697(14) Stable 0+ 0.7899(4) 0.78958–0.79017
25Mg 12 13 24.98583696(5) Stable 5/2+ 0.1000(1) 0.09996–0.10012
26Mg[n 6] 12 14 25.98259297(3) Stable 0+ 0.1101(3) 0.10987–0.11030
27Mg 12 15 26.98434063(5) 9.435(27) min β− 27Al 1/2+
28Mg 12 16 27.9838766(21) 20.915(9) h β− 28Al 0+
29Mg 12 17 28.988617(12) 1.30(12) s β− 29Al 3/2+
30Mg 12 18 29.990463(4) 313(4) ms β− (99.94%) 30Al 0+
β−, n (0.06%) 29Al
31Mg 12 19 30.996648(3) 236(20) ms β− (93.8%) 31Al 1/2(+)
β−, n (6.2%) 30Al
32Mg 12 20 31.999110(4) 86(5) ms β− (94.5%) 32Al 0+
β−, n (5.5%) 31Al
33Mg 12 21 33.005327(3) 90.5(16) ms β− (86%) 33Al 3/2−
β−, n (14%) 32Al
34Mg 12 22 34.00894(3) 20(10) ms β− (70%) 34Al 0+
β−, n (30%) 33Al
35Mg 12 23 35.01679(29) 70(40) ms β−, n (52%) 34Al 7/2−#
β− (48%) 35Al
36Mg 12 24 36.02188(74) 3.9(13) ms β− 36Al 0+
37Mg 12 25 37.03029(75) 8(4) ms β− 37Al (3/2−)
β−, n 36Al
38Mg 12 26 38.03658(54)# 1# ms [>260 ns] 0+
40Mg 12 28 40.05191(54)# 1# ms β−, n 39Al 0+
β− 40Al
This table header & footer:
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  1. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  2. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  3. ^ Modes of decay:
    n: Neutron emission
    p: Proton emission
  4. ^ Bold symbol as daughter – Daughter product is stable.
  5. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  6. ^ Used in radiodating events early in the Solar System's history

External links[]

References[]

  1. ^ "Standard Atomic Weights: Magnesium". CIAAW. 2011.
  2. ^ Meija, Juris; 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.
  3. ^ Half-life, decay mode, nuclear spin, and isotopic composition is sourced in:
    Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
  4. ^ Wang, M.; Audi, G.; Kondev, F. G.; Huang, W. J.; Naimi, S.; Xu, X. (2017). "The AME2016 atomic mass evaluation (II). Tables, graphs, and references" (PDF). Chinese Physics C. 41 (3): 030003-1–030003-442. doi:10.1088/1674-1137/41/3/030003.
  5. ^ Jin, Y.; et al. (2021). "First observation of the four-proton unbound nucleus 18Mg". Physical Review Letters. 127 (262502). doi:10.1103/PhysRevLett.127.262502.
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