Magnesium-25 is a stable isotope of the chemical element magnesium, which has 13 neutrons in its atomic nucleus in addition to the element-specific 12 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 25. 25Mg is one of the three isotopes that make up the earth's natural magnesium deposits (see below).
In 1920, the physicist Arthur Jeffrey Dempster described the isotopic composition of magnesium for the first time. For his experiments, he used an apparatus for positive ray analysis; the cylindrical anode contained the magnesium and was irradiated with electrons [1].
See also: list of Magnesium isotopes.
Direct parent isotopes are: 25Al, 25Na.
Atomic Mass ma | Quantity | Half-life | Spin | |
---|---|---|---|---|
Magnesium Isotopic mixture | 24.305 u | 100 % | ||
Isotope 24Mg | 23.98504170(9) u | 78.965(49) % [78.88 - 79.05 %] | stable | 0+ |
Isotope 25Mg | 24.9858370(3) u | 10.011 % [9.988 - 10.034 %] | stable | 5/2+ |
Isotope 26Mg | 25.9825930(2) u | 11.024 % [10.96 - 11.09 %] | stable | 0+ |
Nuclear magnetic properties of the NMR active Nuclide 25Mg
Magnesium-25 has the only NMR-active atomic nucleus of the three natural magnesium isotopes. The nuclide is quadrupolar with a spin of 5/2 and has only a low sensitivity. The NMR signal width is narrow in symmetrical environments and increases with the asymmetry of the environment, such as in Grignard compounds. The chemical shift of inorganic magnesium is strongly solvent-dependent. Overall, 25NMR spectroscopy is a rarely used special application.
Z | Isotone N = 13 | Isobar A = 25 |
---|---|---|
5 | 18B | |
6 | 19C | |
7 | 20N | 25N |
8 | 21O | 25O |
9 | 22F | 25F |
10 | 23Ne | 25Ne |
11 | 24Na | 25Na |
12 | 25Mg | 25Mg |
13 | 26Al | 25Al |
14 | 27Si | 25Si |
15 | 28P | 25P |
16 | 29S | |
17 | 30Cl | |
18 | 31Ar | |
19 | 32K |
[1] - A. J. Dempster:
Positive Ray Analysis of Lithium and Magnesium.
In: Physical Review, 18, 415, (1921), DOI 10.1103/PhysRev.18.415.
[2] - Jair C.C. Freitas, Mark E. Smith:
Recent Advances in Solid-State 25Mg NMR Spectroscopy.
In: Annual Reports on NMR Spectroscopy, 75, (2012), DOI 10.1016/B978-0-12-397018-3.00002-8.
Last update: 2024-11-06
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