Of the 22 known isotopes of magnesium, 3 occur as stable nuclei in nature: 24magnesium, 25magnesium and 26magnesium. All other magnesium isotopes are unstable radionuclides, of which 28Mg is the most long-lived with a half-life of about 21 hours.
| Atomic Mass ma | Quantity | Half-life | Spin | |
| Magnesium Isotopic mixture | 24,305 u | 100 % | ||
| Isotope 24Mg | 23,98504170(9) u | 78,965 % | stable | 0+ |
| Isotope 25Mg | 24,9858370(3) u | 10,011 % | stable | 5/2+ |
| Isotope 26Mg | 25,9825930(2) u | 11,024 % | stable | 0+ |
The natural isotope composition (isotope ratio) of naturally occurring magnesium can vary to a greater or lesser extent. The atomic weight of magnesium is therefore given with the interval 24.304 to 24.307 u.
| Isotope Nuclide | E | N | Atomic Mass [Nuclear Mass] {Mass Excess} | Spin I (h/2π) | Parent |
|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 |
| Magnesium-19 | 1912Mg | 7 | 19.03417(5) u [19.0275871 u] {31.82915 MeV} | 1/2- | |
| Magnesium-20 | 2012Mg | 8 | 20.0187631(2) u [20.0121802 u] {17.47772 MeV} | 0+ | |
| Magnesium-21 | 2112Mg | 9 | 21.0117058(8) u [21.0051229 u] {10.90388 MeV} | 5/2+ | 22Si |
| Magnesium-22 | 2212Mg | 10 | 21.9995707(3) u [21.9929878 u] {-0.39989 MeV} | 0+ | 23Si 22Al |
| Magnesium-23 | 2312Mg | 11 | 22.99412394(17) u [22.987541 u] {-5.47351 MeV} | 3/2+ | 24Si 23Al |
| Magnesium-24 | 2412Mg | 12 | 23.98504170(9) u [23.9784588 u] {-13.93357 MeV} | 0+ | 25Si 24Al 24Na 26P 28P |
| Magnesium-25 | 2512Mg | 13 | 24.9858370(3) u [24.9792541 u] {-13.19275 MeV} | 5/2+ | 25Al 25Na |
| Magnesium-26 | 2612Mg | 14 | 25.9825930(2) u [25.9760101 u] {-16.21452 MeV} | 0+ | 26Al 26Na 27Na |
| Magnesium-27 | 2712Mg | 15 | 26.98434063(5) u [26.9777577 u] {-14.58661 MeV} | 1/2+ | 27Na |
| Magnesium-28 | 2812Mg | 16 | 27.9838766(21) u [27.9772937 u] {-15.01885 MeV} | 0+ | 28Na 29Na |
| Magnesium-29 | 2912Mg | 17 | 28.988617(12) u [28.9820341 u] {-10.6032 MeV} | 3/2+ | 29Na 30Na 31Na |
| Magnesium-30 | 3012Mg | 18 | 29.990463(4) u [29.9838801 u] {-8.88366 MeV} | 0+ | 30Na 31Na 32Na |
| Magnesium-31 | 3112Mg | 19 | 30.996648(3) u [30.9900651 u] {-3.12237 MeV} | 1/2(+) | 31Na 32Na 33Na |
| Magnesium-32 | 3212Mg | 20 | 31.999110(4) u [31.9925271 u] {-0.82903 MeV} | 0+ | 32Na 33Na 34Na |
| Magnesium-33 | 3312Mg | 21 | 33.005327(3) u [32.9987441 u] {4.96207 MeV} | 3/2- | 33Na 34Na |
| Magnesium-34 | 3412Mg | 22 | 34.00894(3) u [34.0023571 u] {8.32756 MeV} | 0+ | 34Na 35Na |
| Magnesium-35 | 3512Mg | 23 | 35.01679(29) u [35.0102071 u] {15.63978 MeV} | (5/2-) | 35Na |
| Magnesium-36 | 3612Mg | 24 | 36.02188(74) u [36.0152971 u] {20.38109 MeV} | 0+ | |
| Magnesium-37 | 3712Mg | 25 | 37.03029(75) u [37.0237071 u] {28.21495 MeV} | (7/2-) | |
| Magnesium-38 | 3812Mg | 26 | 38.03658(54) u [38.0299971 u] {34.07405 MeV} | 0+ | |
| Magnesium-39 | 3912Mg | 27 | 39.04538(55) u [39.0387971 u] {42.2712 MeV} | ||
| Magnesium-40 | 4012Mg | 28 | 40.05191(54) u [40.0453271 u] {48.35385 MeV} | 0+ |
| Isotope | Radioactive Decay | Extern | |||
|---|---|---|---|---|---|
| Half-life | Decay Mode | Probability | Energy | ||
| 7 | 8 | 9 | 10 | 11 | 12 |
| Mg-19 | 5(3) ps | 2p → 17Ne | ca. 100 % | AL | |
| Mg-20 | 93(5) ms | β+ → 20Na β+, p → 19Ne | 69.7 % 30.3(12) % | 10.6271(22) MeV 8.530 MeV | AL |
| Mg-21 | 122(3) ms | EC/β+ → 21Na β+, p → 20Ne β+, α → 16F | 66.9 % 32.6 % 0.5 % | 13.0885(8) MeV 10.663 MeV 6.534 MeV | AL |
| Mg-22 | 3.8755(12) s | EC β+ → 22Na | 100 % | 4.7816(4) MeV | AL |
| Mg-23 | 11.317(11) s | EC β+ → 23Na | 100 % | 4.05634(16) MeV | AL |
| Mg-24 | stable | AL | |||
| Mg-25 | stable | AL | |||
| Mg-26 | stable | AL | |||
| Mg-27 | 9.458(12) min | β- → 27Al | 100 % | 2.61025(7) MeV | AL |
| Mg-28 | 20.915(9) h | β- → 28Al | 100 % | 1.8318(20) MeV | AL |
| Mg-29 | 1.30(12) s | β- → 29Al | 100 % | 7.61254 MeV | AL |
| Mg-30 | 335(17) ms | β- → 30Al | 100 % | 6.98041 MeV | AL |
| Mg-31 | 236(20) ms | β- → 31Al β-, n → 30Al | 93.8 % 6.2(19) % | 11.7646 MeV 4.61077 MeV | AL |
| Mg-32 | 86(5) ms | β- → 32Al β-, n → 31Al | 94.5(5) % 5.5(5) % | 10.15028 MeV 5.97199 MeV | AL |
| Mg-33 | 90.5(16) ms | β- → 33Al β-, n → 32Al | 86(2) % 14(2) % | 13.38438 MeV 7.93781 MeV | AL |
| Mg-34 | 20(10) ms | β- → 34Al β-, n → 33Al | 11.60756 MeV 8.9263 MeV | AL | |
| Mg-35 | 11.3(6) ms | β- → 35Al β-, n → 34Al β-, 2n ? β-, 3n ? | 48 % 52 % | 15.85962 MeV 10.6156 MeV | AL |
| Mg-36 | 3.9(13) ms | β- → 36Al β-, n → 35Al | 14.42978 MeV 12.5287 MeV | AL | |
| Mg-37 | 8(4) ms | β- → 37Al β-, n 36Al β-, 2n 35Al | ? ? ? | 18.40(72) MeV 14.19(71) MeV | AL |
| Mg-38 | 260 ns | β- → 38Al β-, n → 37Al β-, n → 36Al | 100 % ? ? | 17.86(63) MeV 16.19(53) MeV | AL |
| Mg-39 | 180 ns | n ? | AL | ||
| Mg-40 | 170 ns | β- ? 40Al β-, n 39Al β-, 2n 38Al | 100 % ? ? | 20.76(64) MeV 19.63(64) MeV | AL |
Notes (related to the columns):
1 - name of the nuclide, isotope.
2 - E: isotope symbol with mass number (superscript; number of nucleons) and Atomic number (subscript; number of protons).
3 - N: number of neutrons.
4 - relative atomic mass of the Magnesium isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
5 - nuclear spin I, unit: h/2π.
6 - source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.
7 - isotope notation in short form.
8 - decay: half-live of the Magnesium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
9 - decay mode: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
10 - decay probability in percent (%).
11 - decay energy; Particle energy related to decay type.
12 - other information and notes: AL = Adopted Levels (link to external data [1]).
Miscellaneous:
()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
- unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.
| Nuclide quantity 1) spin | Nuclear magnetic moment μ/μN | Gyromagnetic ratio {Quadrupole moment} | Resonant frequency v0 bei 1 T | Relative sensitivity H0 = const. v0 = const. 3) |
|---|---|---|---|---|
| 25Mg 10,011 % 5/2+ | -0,85533(3) | - 1,639 {+ 0,1994(20)} | 2,6083 | 0,002698 0,7147 |
1) Quantity Percentage of natural occurrence.
2) Gyromagnetic ratio: 107 rad T-1 s-1
Quadrupole moment: Q [barn] = [100 fm2]
3) Related to 1H = 1,000.
According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Magnesium radionuclides:
| Nuclide | Limit Value | HASS limit | SC | Daughter Nuclides | Half-life | |
|---|---|---|---|---|---|---|
| Mg-28+ | 105 Bq | 1 Bq/g | 0,02 TBq | Al-28 | 20.9 h | |
(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)
Properties of the Magnesium nucleides
[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.
[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.
[3] - Live Chart of Nuclides. Nuclear structure and decay data.
Magnesium: NMR properties - 25Mg-NMR
[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.
[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.
[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.
[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).
More sources:
[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.
Last update: 2022-12-12
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