Isotopes of magnesium

Isotopes of magnesium (₁₂Mg)
Standard atomic weight Ar°(Mg)
	[24.304, 24.307]; 24.305±0.002 (abridged);
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Magnesium (₁₂Mg) naturally occurs in three stable isotopes: ²⁴
Mg, ²⁵
Mg, and ²⁶
Mg. There are 19 radioisotopes that have been discovered, ranging from ¹⁸
Mg to ⁴⁰
Mg (with the exception of ³⁹
Mg). The longest-lived radioisotope is ²⁸
Mg with a half-life of 20.915(9) h. The lighter isotopes mostly decay to isotopes of sodium while the heavier isotopes decay to isotopes of aluminium. The shortest-lived is proton-unbound ¹⁸
Mg with a half-life of 4.0(3.4) zeptoseconds.

A precise measurement of the neutron-rich ⁴⁰Mg in 2019 showed the unexpected difference in its nuclear structure, compared to the lighter neighboring isotopes.^[4]^[5]

The abundances of the naturally occurring isotopes of magnesium.

List of isotopes

Nuclide	Z	N	Isotopic mass (Da)^[6] ^{[n 1]}	Half-life^[1] ^{[n 2]}	Decay mode^[1] ^{[n 3]}	Daughter isotope ^{[n 4]}	Spin and parity^[1] ^{[n 5]}^{[n 2]}	Natural abundance (mole fraction)
Nuclide	Z	N	Isotopic mass (Da)^[6] ^{[n 1]}	Half-life^[1] ^{[n 2]}	Decay mode^[1] ^{[n 3]}	Daughter isotope ^{[n 4]}	Spin and parity^[1] ^{[n 5]}^{[n 2]}	Normal proportion^[1]	Range of variation
¹⁸ Mg^[7]	12	6		4.0(3.4) zs	2p	¹⁶ Ne	0+
¹⁹ Mg	12	7	19.034180(60)	5(3) ps	2p	¹⁷ Ne	1/2−#
²⁰ Mg	12	8	20.0187631(20)	90.4(5) ms	β⁺ (69.7(1.2)%)	²⁰ Na	0+
²⁰ Mg	12	8	20.0187631(20)	90.4(5) ms	β⁺p (30.3(1.2)%)	¹⁹ Ne	0+
²¹ Mg	12	9	21.0117058(8)	120.0(4) ms	β⁺ (79.8(2.1)%)	²¹ Na	5/2+
					β⁺p (20.1(2.1)%)	²⁰ Ne
					β⁺α (0.116(18)%)	¹⁷ F
					β⁺pα (0.016(3)%)	¹⁶ O
²² Mg	12	10	21.99957060(17)	3.8745(7) s	β⁺	²² Na	0+
²³ Mg	12	11	22.99412377(3)	11.3039(32) s	β⁺	²³ Na	3/2+
²⁴ Mg	12	12	23.985041689(14)	Stable			0+	[0.7888, 0.7905]
²⁵ Mg	12	13	24.98583697(5)	Stable			5/2+	[0.09988, 0.10034]
²⁶ Mg^{[n 6]}	12	14	25.98259297(3)	Stable			0+	[0.1096, 0.1109]
²⁷ Mg	12	15	26.98434065(5)	9.435(27) min	β⁻	²⁷ Al	1/2+
²⁸ Mg	12	16	27.98387543(28)	20.915(9) h	β⁻	²⁸ Al	0+
²⁹ Mg	12	17	28.9886072(4)	1.30(12) s	β⁻	²⁹ Al	3/2+
³⁰ Mg	12	18	29.9904655(14)	317(4) ms	β⁻ (> 99.94%)	³⁰ Al	0+
³⁰ Mg	12	18	29.9904655(14)	317(4) ms	β⁻n (< 0.06%)	²⁹ Al	0+
³¹ Mg	12	19	30.996648(3)	270(2) ms	β⁻ (93.8(1.9)%)	³¹ Al	1/2+
³¹ Mg	12	19	30.996648(3)	270(2) ms	β⁻n (6.2(1.9)%)	³⁰ Al	1/2+
³² Mg	12	20	31.999110(4)	80.4(4) ms	β⁻ (94.5(5)%)	³² Al	0+
³² Mg	12	20	31.999110(4)	80.4(4) ms	β⁻n (5.5(5)%)	³¹ Al	0+
³³ Mg	12	21	33.0053279(29)	92.0(1.2) ms	β⁻ (86(2)%)	³³ Al	3/2−
					β⁻n (14(2)%)	³² Al
					β⁻2n ?^{[n 7]}	³¹ Al ?
³⁴ Mg	12	22	34.008935(7)	44.9(4) ms	β⁻ (> 78.9(7.0)%)	³⁴ Al	0+
					β⁻n (21(7)%)	³³ Al
					β⁻2n (< 0.1%)	³² Al
³⁵ Mg	12	23	35.01679(29)	11.3(6) ms	β⁻n (52(46)%)	³⁴ Al	(3/2−, 5/2−)
					β⁻ (48(46)%)	³⁵ Al
					β⁻2n ?^{[n 7]}	³³ Al ?
³⁶ Mg	12	24	36.02188(74)	3.9(1.3) ms	β⁻ (52(12)%)	³⁶ Al	0+
					β⁻n (48(12)%)	³⁵ Al
					β⁻2n ?^{[n 7]}	³⁴ Al ?
³⁷ Mg	12	25	37.03029(75)	8(4) ms	β⁻ ?^{[n 7]}	³⁷ Al ?	(3/2−)
					β⁻n ?^{[n 7]}	³⁶ Al ?
					β⁻2n ?^{[n 7]}	³⁵ Al ?
³⁸ Mg	12	26	38.03658(54)#	3.1(4 (stat), 2 (sys)) ms^[8]	β⁻n (81%)	³⁷ Al	0+
					β⁻ (9%)	³⁸ Al
					β⁻2n (9%)	³⁶ Al
⁴⁰ Mg	12	28	40.05319(54)#	1# ms [> 170 ns]	β⁻ ?^{[n 7]}	⁴⁰ Al ?	0+
					β⁻n ?^{[n 7]}	³⁹ Al ?
					β⁻2n ?^{[n 7]}	³⁸ Al ?
This table header & footer: view

^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
^ ^a ^b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
^ Modes of decay:

n: Neutron emission

p: Proton emission
^ Bold symbol as daughter – Daughter product is stable.
^ ( ) spin value – Indicates spin with weak assignment arguments.
^ Used in radiodating events early in the Solar System's history
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.

External links

Magnesium isotopes data from The Berkeley Laboratory Isotopes Project's

References

^ ^a ^b ^c ^d ^e Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
^ "Standard Atomic Weights: Magnesium". CIAAW. 2011.
^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
^ glennroberts (2019-02-07). "New Measurements of Exotic Magnesium Suggest Surprising Shape-Shift". Berkeley Lab News Center. Retrieved 2023-09-10.
^ "NP A Change in Structure for a S... | U.S. DOE Office of Science(SC)". science.osti.gov. 2019-08-01. Retrieved 2023-09-10.
^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
^ Jin, Y.; et al. (2021). "First observation of the four-proton unbound nucleus ¹⁸Mg". Physical Review Letters. 127 (262502): 262502. doi:10.1103/PhysRevLett.127.262502. OSTI 1837749. PMID 35029460. S2CID 245434485.
^ Crawford, H. L.; Tripathi, V.; Allmond, J. M.; et al. (2022). "Crossing N = 28 toward the neutron drip line: first measurement of half-lives at FRIB". Physical Review Letters. 129 (212501): 212501. Bibcode:2022PhRvL.129u2501C. doi:10.1103/PhysRevLett.129.212501. PMID 36461950. S2CID 253600995.

[7] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TNN-8] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[9] Modes of decay:

n: Neutron emission

p: Proton emission

[10] Bold symbol as daughter – Daughter product is stable.

[11] ( ) spin value – Indicates spin with weak assignment arguments.

[13] Used in radiodating events early in the Solar System's history

[decay_mode_1-14] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.

[NUBASE2020-1] Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[2] "Standard Atomic Weights: Magnesium". CIAAW. 2011.

[CIAAW2021-3] Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[4] roberts (2019-02-07). "New Measurements of Exotic Magnesium Suggest Surprising Shape-Shift". Berkeley Lab News Center. Retrieved 2023-09-10.

[5] "NP A Change in Structure for a S... | U.S. DOE Office of Science(SC)". science.osti.gov. 2019-08-01. Retrieved 2023-09-10.

[AME2020_II-6] Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.

[18Mg-12] Jin, Y.; et al. (2021). "First observation of the four-proton unbound nucleus ¹⁸Mg". Physical Review Letters. 127 (262502): 262502. doi:10.1103/PhysRevLett.127.262502. OSTI 1837749. PMID 35029460. S2CID 245434485.

[NR129-15] Crawford, H. L.; Tripathi, V.; Allmond, J. M.; et al. (2022). "Crossing N = 28 toward the neutron drip line: first measurement of half-lives at FRIB". Physical Review Letters. 129 (212501): 212501. Bibcode:2022PhRvL.129u2501C. doi:10.1103/PhysRevLett.129.212501. PMID 36461950. S2CID 253600995.

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