Isotopes of magnesium

Magnesium (Mg) naturally occurs in three stable isotopes, ²⁴Mg, ²⁵Mg, and ²⁶Mg. 19 radioisotopes 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 aluminum. The shortest-lived is ³⁹Mg with a half-life shorter than 180 nanoseconds, or rarely ⁴⁰Mg, with a half-life longer than 170 nanoseconds (the half-life of ¹⁹Mg is unknown).

Standard atomic mass: 24.3050(6) u

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[1]	daughter isotope(s)^{[n 1]}	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+
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%)	¹⁶F
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

References

Isotope masses from:
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
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 and 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. http://www.iupac.org/publications/pac/75/6/0683/pdf/.
- 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. http://iupac.org/publications/pac/78/11/2051/pdf/. 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 and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005.
- 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 978-0849304859.

External links

Magnesium isotopes data from The Berkeley Laboratory Isotopes Project's

^ http://www.nucleonica.net/unc.aspx

Isotopes of sodium	Isotopes of magnesium	Isotopes of aluminium
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