Isotopes of magnesium

Main isotopes of magnesium

Isotope			Decay
	abundance	half-life (t_1/2)	mode	product
²⁴Mg	79.0%	stable
²⁵Mg	10.0%	stable
²⁶Mg	11.0%	stable

Standard atomic weight (A_r)

[24.304, 24.307]^[1]
Conventional: 24.305

Magnesium (₁₂Mg) 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 ¹⁹Mg with a half-life of 4 picoseconds.

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

List of isotopes

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[2]	daughter isotope(s)^{[n 1]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
¹⁹Mg	12	7	19.03547(27)	4×10⁻¹² s	2p	¹⁷Ne	1/2−#
²⁰Mg	12	8	20.018863(29)	90.8(24) ms	β⁺ (97%)	²⁰Na	0+
²⁰Mg	12	8	20.018863(29)	90.8(24) ms	β⁺, p (3%)	¹⁹Ne	0+
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^{[n 2]}	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+
³⁰Mg	12	18	29.990434(9)	335(17) ms	β⁻, n (.06%)	²⁹Al	0+
³¹Mg	12	19	30.996546(13)	230(20) ms	β⁻ (98.3%)	³¹Al	3/2+
³¹Mg	12	19	30.996546(13)	230(20) ms	β⁻, n (1.7%)	³⁰Al	3/2+
³²Mg	12	20	31.998975(19)	86(5) ms	β⁻ (97.6%)	³²Al	0+
³²Mg	12	20	31.998975(19)	86(5) ms	β⁻, n (2.4%)	³¹Al	0+
³³Mg	12	21	33.005254(21)	90.5(16) ms	β⁻ (83%)	³³Al	7/2−#
³³Mg	12	21	33.005254(21)	90.5(16) ms	β⁻, n (17%)	³²Al	7/2−#
³⁴Mg	12	22	34.00946(25)	20(10) ms	β⁻ (>99.9%)	³⁴Al	0+
³⁴Mg	12	22	34.00946(25)	20(10) ms	β⁻, n (<.1%)	³³Al	0+
³⁵Mg	12	23	35.01734(43)#	70(40) ms	β⁻, n (52%)	³⁴Al	(7/2−)#
³⁵Mg	12	23	35.01734(43)#	70(40) ms	β⁻ (48%)	³⁵Al	(7/2−)#
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−#
³⁷Mg	12	25	37.03140(97)#	40# ms [>260 ns]	β⁻, n	³⁶Al	7/2−#
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+

↑ Bold for stable isotopes
↑ Used in radiodating events early in the Solar System's history

Notes

Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

References

Isotope masses from:
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
Isotopic compositions and standard atomic masses from:
- J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. Check date values in: |access-date= (help)
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.

External links

Magnesium isotopes data from The Berkeley Laboratory Isotopes Project's

↑ Meija, J.; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure Appl. Chem. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
↑ "Universal Nuclide Chart". nucleonica. (Registration required (help)).

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

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