Isotopes of magnesium

Magnesium (Mg) naturally occurs in three stable isotopes, ²⁴Mg, ²⁵Mg, and ²⁶Mg. There are 19 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 ³⁹Mg with a half-life shorter than 180 nanoseconds, or possibly ⁴⁰Mg, with a half-life longer than 170 nanoseconds (the half-life of ¹⁹Mg is unknown).

Relative atomic mass: 24.3050(6)

File:Magnesium chart.png

A chart showing the abundances of the naturally-occurring isotopes of magnesium.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
19Mg	12	7	19.03547(27)				1/2−#
20Mg	12	8	20.018863(29)	90.8(24) ms	β+ (97%)	20Na	0+
					β+, p (3%)	19Ne
21Mg	12	9	21.011713(18)	122(2) ms	β+ (66.9%)	21Na	(5/2,3/2)+
					β+, p (32.6%)	20Ne
					β+, α (0.5%)	17F
22Mg	12	10	21.9995738(14)	3.8755(12) s	β+	22Na	0+
23Mg	12	11	22.9941237(14)	11.317(11) s	β+	23Na	3/2+
24Mg	12	12	23.985041700(14)	Stable			0+	0.7899(4)	0.78958–0.79017
25Mg	12	13	24.98583692(3)	Stable			5/2+	0.1000(1)	0.09996–0.10012
26Mg	12	14	25.982592929(30)	Stable			0+	0.1101(3)	0.10987–0.11030
27Mg	12	15	26.98434059(5)	9.458(12) min	β−	27Al	1/2+
28Mg	12	16	27.9838768(22)	20.915(9) h	β−	28Al	0+
29Mg	12	17	28.988600(15)	1.30(12) s	β−	29Al	3/2+
30Mg	12	18	29.990434(9)	335(17) ms	β− (99.94%)	30Al	0+
					β−, n (.06%)	29Al
31Mg	12	19	30.996546(13)	230(20) ms	β− (98.3%)	31Al	3/2+
					β−, n (1.7%)	30Al
32Mg	12	20	31.998975(19)	86(5) ms	β− (97.6%)	32Al	0+
					β−, n (2.4%)	31Al
33Mg	12	21	33.005254(21)	90.5(16) ms	β− (83%)	33Al	7/2−#
					β−, n (17%)	32Al
34Mg	12	22	34.00946(25)	20(10) ms	β− (>99.9%)	34Al	0+
					β−, n (<.1%)	33Al
35Mg	12	23	35.01734(43)#	70(40) ms	β−, n (52%)	34Al	(7/2−)#
					β− (48%)	35Al
36Mg	12	24	36.02300(54)#	3.9(13) ms	β−	36Al	0+
37Mg	12	25	37.03140(97)#	40# ms [>260 ns]	β−	37Al	7/2−#
					β−, n	36Al
38Mg	12	26	38.03757(54)#	1# ms [>260 ns]			0+
39Mg	12	27	39.04677(55)#	<260 ns			7/2−#
40Mg	12	28	40.05393(97)#	1# ms			0+

References

• Isotope masses from:
• Isotopic compositions and standard atomic masses from:
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.

External links

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

Isotopes of sodium	Isotopes of magnesium	Isotopes of aluminium
Table of nuclides