Isotopes of magnesium

Magnesium (₁₂Mg) naturally occurs in three stable isotopes, ²⁴Mg, ²⁵Mg, and ²⁶Mg. There are 18 radioisotopes that have been discovered, ranging from ¹⁹Mg 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 ¹⁹Mg with a half-life of 5 picoseconds.

The abundances of the naturally occurring isotopes of magnesium.

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][1] Conventional: 24.305

List of isotopes

Nuclide[2]	Z	N	Isotopic mass (Da)[3] [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
^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

1. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
2. # – 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

• Magnesium isotopes data from The Berkeley Laboratory Isotopes Project's

References

1. 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.
2. 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.
3. 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.