Isotopes of sodium

There are 21 recognized isotopes of sodium (₁₁Na), ranging from ¹⁸
Na to ³⁹
Na[2] and two isomers (^22m
Na and ^24m
Na). ²³
Na is the only stable (and the only primordial) isotope. It is considered a monoisotopic element and it has a standard atomic weight of 22.98976928(2). Sodium has two radioactive cosmogenic isotopes (²²
Na, half-life = 2.605 years; and ²⁴
Na, half-life ≈ 15 hours). With the exception of those two, all other isotopes have half-lives under a minute, most under a second. The shortest-lived is ¹⁸
Na, with a half-life of 1.3(4)×10⁻²¹ seconds.

Main isotopes of sodium (₁₁Na)

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct ^22Na trace 2.602 y β^+ ^22Ne ^23Na 100% stable ^24Na trace 14.96 h β^− ^24Mg
Standard atomic weight Ar, standard(Na)	22.98976928(2)[1]

Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable ²³
Na in human blood plasma to ²⁴
Na. By measuring the concentration of this isotope, the neutron radiation dosage to the victim can be computed.

²²
Na is a positron-emitting isotope with a remarkably long half-life. It is used to create test-objects and point-sources for positron emission tomography.

List of isotopes

Nuclide[3] [n 1]	Z	N	Isotopic mass (Da)[4] [n 2][n 3]	Half-life [n 4]	Decay mode [n 5]	Daughter isotope [n 6]	Spin and parity [n 7][n 4]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
^18Na	11	7	18.02688(10)	1.3(4)×10^−21 s	p	^17Ne	(1−)#
					β^+ (<.1%)	^18Ne
^19Na	11	8	19.013880(11)	>10×10^−18 s	p	^18Ne	(5/2+)
^20Na	11	9	20.0073544(12)	447.9(23) ms	β^+ (75%)	^20Ne	2+
					β^+, α (25%)	^16O
^21Na	11	10	20.99765470(11)	22.422(10) s	β^+	^21Ne	3/2+
^22Na	11	11	21.99443742(18)	2.6018(22) y	β^+	^22Ne	3+	Trace[n 8]
^22m1Na	583.03(9) keV			243(2) ns	IT	^22Na	1+
^22m2Na	657.00(14) keV			19.6(7) ps	IT	^22Na	0+
^23Na	11	12	22.9897692820(19)	Stable			3/2+	1.0000
^24Na	11	13	23.990963011(18)	14.957(4) h	β^−	^24Mg	4+	Trace[n 8]
^24mNa	472.207(9) keV			20.18(10) ms	IT (99.95%)	^24Na	1+
					β^− (.05%)	^24Mg
^25Na	11	14	24.9899540(13)	59.1(6) s	β^−	^25Mg	5/2+
^26Na	11	15	25.992635(4)	1.07128(25) s	β^−	^26Mg	3+
^26mNa	82.5(6) keV			9(2) µs	IT	^26Na	1+
^27Na	11	16	26.994076(4)	301(6) ms	β^− (99.87%)	^27Mg	5/2+
					β^−, n (0.13%)	^26Mg
^28Na	11	17	27.998939(11)	30.5(4) ms	β^− (99.42%)	^28Mg	1+
					β^−, n (0.58%)	^27Mg
^29Na	11	18	29.002877(8)	44.1(9) ms	β^− (74.1%)	^29Mg	3/2(+#)
					β^−, n (25.9%)	^28Mg
^30Na	11	19	30.009098(5)	48.4(17) ms	β^− (68.85%)	^30Mg	2+
					β^−, n (30.0%)	^29Mg
					β^−, 2n (1.15%)	^28Mg
					β^−, α (5.5×10^−5%)	^26Ne
^31Na	11	20	31.013147(15)	17.35(40) ms	β^− (61.78%)	^31Mg	(3/2+)
					β^−, n (37.3%)	^30Mg
					β^−, 2n (0.87%)	^29Mg
					β^−, 3n (0.05%)	^28Mg
^32Na	11	21	32.02001(4)	12.9(3) ms	β^− (68%)	^32Mg	(3−)
					β^−, n (24%)	^31Mg
					β^−, 2n (8%)	^30Mg
^33Na	11	22	33.02553(48)	8.2(4) ms	β^−, n (47%)	^32Mg	(3/2+)
					β^− (40%)	^33Mg
					β^−, 2n (13%)	^31Mg
^34Na	11	23	34.03401(64)	5.5(10) ms	β^−, 2n (50.0%)	^32Mg	1+
					β^− (35.0%)	^34Mg
					β^−, n (15.0%)	^33Mg
^35Na	11	24	35.04104(72)#	1.5(5) ms	β^−	^35Mg	3/2+#
^37Na	11	26	37.05747(74)#	1# ms [>1.5 µs]	β^−, n	^36Mg	3/2+#
^39Na[2]	11	28			β^−, n (#)	^38Mg

1. ^mNa – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. Modes of decay:

   IT:	Isomeric transition
   n:	Neutron emission
   p:	Proton emission

6. Bold symbol as daughter – Daughter product is stable.
7. ( ) spin value – Indicates spin with weak assignment arguments.
8. Cosmogenic nuclide

Sodium-22

Sodium-22 is a radioactive isotope of sodium, undergoing positron emission to ²²
Ne with a half-life of 2.605 years. ²²
Na is being investigated as an efficient generator of "cold positrons" (antimatter) to produce muons for catalyzing fusion of deuterium. It is also commonly used as a positron source in positron annihilation spectroscopy[5].

Sodium-24

Sodium-24 is one of the most important isotopes. It is radioactive and created from common sodium-23 by neutron bombardment. With a 15-hour half-life, ²⁴
Na decays to ²⁴
Mg by emission of an electron and two gamma rays. Exposure of the human body to intense neutron flux creates ²⁴
Na in blood plasma. Measurements of its quantity are used to determine the absorbed radiation dose of the patient. This is used to determine the level of medical treatment required.

When the sodium-potassium alloy is used as a coolant in nuclear reactors, ²⁴
Na is created, which makes the coolant radioactive. When the ²⁴
Na decays, it causes a buildup of magnesium in the coolant. Since the half life is short, the ²⁴
Na portion of the coolant ceases to be radioactive within a few days after removal from the reactor.

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. Ahn, D.S.; et al. (2018). New isotope of ³⁹Na and the neutron dripline of neon isotopes using a 345 MeV/nucleon ⁴⁸Ca beam (PDF) (Report). RIKEN Accelerator Progress Reports. 51. p. 82.
3. 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.
4. 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.
5. Saro, Matúš; Kršjak, Vladimír; Petriska, Martin; Slugeň, Vladimír (2019-07-29). "Sodium-22 source contribution determination in positron annihilation measurements using GEANT4". AIP Conference Proceedings. 2131 (1): 020039. doi:10.1063/1.5119492. ISSN 0094-243X.

External links

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