Physics:Isotopes of sodium

Short description: Nuclides with atomic number of 11 but with different mass numbers

Main isotopes of Chemistry: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)

There are 20 isotopes of sodium (₁₁Na), ranging from ¹⁷Na to ³⁹Na (except for the still-unknown ³⁶Na and ³⁸Na), and two isomers (^22mNa and ^24mNa). ²³Na 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 (²²Na, with a half-life of 2.6019(6) years; and ²⁴Na, with a half-life of 14.9560(15) h). With the exception of those two isotopes, all other isotopes have half-lives under a minute, most under a second. The shortest-lived is the unbound ¹⁸Na, with a half-life of 1.3(4)×10⁻²¹ seconds (although the half-life of the similarly unbound ¹⁷Na is not measured).

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

²²Na 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	Z	N	Isotopic mass (u)	Half-life	Decay mode	Daughter isotope	Spin and parity	Physics:Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
17Na	11	6	17.037270(60)		p	16Ne	(1/2+)
18Na	11	7	18.02688(10)	1.3(4) zs	p=?	17Ne	1−#
19Na	11	8	19.013880(11)	> 1 as	p	18Ne	(5/2+)
20Na	11	9	20.0073543(12)	447.9(2.3) ms	β+ (75.0(4)%)	20Ne	2+
					β+α (25.0(4)%)	16O
21Na	11	10	20.99765446(5)	22.4550(54) s	β+	21Ne	3/2+
22Na	11	11	21.99443742(18)	2.6019(6) y	β+ (90.57(8)%)	22Ne	3+	Trace
					ε (9.43(6)%)	22Ne
22m1Na	583.05(10) 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
24Na	11	13	23.990963012(18)	14.9560(15) h	β−	24Mg	4+	Trace
24mNa	472.2074(8) keV			20.18(10) ms	IT (99.95%)	24Na	1+
					β− (0.05%)	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	82.4(4) keV			4.35(16) μs	IT	26Na	1+
27Na	11	16	26.994076(4)	301(6) ms	β− (99.902(24)%)	27Mg	5/2+
					β−n (0.098(24)%)	26Mg
28Na	11	17	27.998939(11)	33.1(1.3) ms	β− (99.42(12)%)	28Mg	1+
					β−n (0.58(12)%)	27Mg
29Na	11	18	29.002877(8)	43.2(4) ms	β− (78%)	29Mg	3/2+
					β−n (22(3)%)	28Mg
					β−2n ?	27Mg ?
30Na	11	19	30.009098(5)	45.9(7) ms	β− (70.2(2.2)%)	30Mg	2+
					β−n (28.6(2.2)%)	29Mg
					β−2n (1.24(19)%)	28Mg
					β−α (5.5(2)%×10−5)	26Ne
31Na	11	20	31.013147(15)	16.8(3) ms	β− (> 63.2(3.5)%)	31Mg	3/2+
					β−n (36.0(3.5)%)	30Mg
					β−2n (0.73(9)%)	29Mg
					β−3n (< 0.05%)	28Mg
32Na	11	21	32.020010(40)	12.9(3) ms	β− (66.4(6.2)%)	32Mg	(3−)
					β−n (26(6)%)	31Mg
					β−2n (7.6(1.5)%)	30Mg
33Na	11	22	33.02553(48)	8.2(4) ms	β−n (47(6)%)	32Mg	(3/2+)
					β− (40.0(6.7)%)	33Mg
					β−2n (13(3)%)	31Mg
34Na	11	23	34.03401(64)	5.5(1.0) ms	β−2n (~50%)	32Mg	1+
					β− (~35%)	34Mg
					β−n (~15%)	33Mg
35Na	11	24	35.04061(72)#	1.5(5) ms	β−	35Mg	3/2+#
					β−n ?	34Mg ?
					β−2n ?	33Mg ?
37Na	11	26	37.05704(74)#	1# ms [> 1.5 μs]	β− ?	37Mg ?	3/2+#
					β−n ?	36Mg ?
					β−2n ?	35Mg ?
39Na	11	28	39.07512(80)#	1# ms [> 400 ns]	β− ?	39Mg ?	3/2+#
					β−n ?	38Mg ?
					β−2n ?	37Mg ?

Sodium-22

Sodium-22 is a radioactive isotope of sodium, undergoing positron emission to ²²Ne with a half-life of 2.6019(6) years. ²²Na 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.

Sodium-23

Sodium-23 is an isotope of sodium with an atomic mass of 22.98976928. It is the only stable isotope of sodium, and because of its abundance, it has been used for nuclear magnetic resonance in various research fields, including materials science and battery research. Sodium-23 relaxation has applications in studying cation-biomolecule interactions, intracellular and extracellular sodium, ion transport in batteries, and quantum information processing.

Sodium-24

Sodium-24 is radioactive and can be created from common sodium-23 by neutron activation. With a half-life of 14.9560(15) h, ²⁴Na decays to ²⁴Mg by emission of an electron and two gamma rays.

Exposure of the human body to intense neutron radiation creates ²⁴Na in the blood plasma. Measurements of its quantity can be done to determine the absorbed radiation dose of a patient. This can be used to determine the type of medical treatment required.

When sodium is used as coolant in fast breeder reactors, ²⁴Na is created, which makes the coolant radioactive. When the ²⁴Na decays, it causes a buildup of magnesium in the coolant. Since the half-life is short, the ²⁴Na portion of the coolant ceases to be radioactive within a few days after removal from the reactor. Leakage of the hot sodium from the primary loop may cause radioactive fires, as it can ignite in contact with air (and explodes in contact with water). For this reason the primary cooling loop is within a containment vessel.

Sodium has been proposed as a casing for a salted bomb, as it would convert to ²⁴Na and produce intense gamma-ray emissions for a few days.

External links

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