Physics:Isotopes of sodium

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 21 known isotopes of sodium (₁₁Na), ranging from ¹⁷Na to ³⁹Na (except for ³⁶Na and ³⁸Na), and five isomers. ²³Na is the only stable (and the only primordial) isotope, making sodium a monoisotopic (and mononuclidic) element. Sodium has two radioactive cosmogenic isotopes (²²Na, with a half-life of 2.6019 years and ²⁴Na, with a half-life of 14.956 hours). With the exception of those two isotopes, all other isotopes have half-lives under a minute, most under a second.

Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable ²³Na in human blood plasma to ²⁴Na. The neutron radiation dose absorbed by the patient can be assessed by measuring the concentration of the radioisotope.

²²Na is a positron-emitting isotope with a relatively long half-life, about 2.6 years. 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
	11	6	17.037270(60)	2017		p		(1/2+)
	11	7	18.02688(10)	2004	1.3(4) zs	p ?		1−#
	11	8	19.013880(11)	1969	> 1 as	p		(5/2+)
	11	9	20.0073543(12)	1950	447.9(2.3) ms	β+ (75.0(4)%)		2+
						β+α (25.0(4)%)
	11	10	20.99765446(5)	1940	22.4550(54) s	β+		3/2+
[[Sodium-22|]]	11	11	21.99443755(14)	1935	2.6019(6) y	β+ (90.57(8)%)		3+	Trace
						ε (9.43(6)%)
	583.05(10) keV			1958	243(2) ns	IT		1+
[[Sodium-23|]]	11	12	22.9897692820(19)	1918	Stable			3/2+	1
[[Sodium-24|]]	11	13	23.990963012(18)	1934	14.9560(15) h	β−		4+	Trace
	472.2074(8) keV			1956	20.18(10) ms	IT (99.95%)		1+
						β− (0.05%)
	11	14	24.9899540(13)	1943	59.1(6) s	β−		5/2+
	11	15	25.992635(4)	1958	1.07128(25) s	β−		3+
	82.4(4) keV			(1987)	4.35(16) μs	IT		1+
	11	16	26.994076(4)	1968	301(6) ms	β− (99.902(24)%)		5/2+
						β−n (0.098(24)%)
	11	17	27.998939(11)	1969	33.1(1.3) ms	β− (99.42(12)%)		1+
						β−n (0.58(12)%)
	11	18	29.002877(8)	1969	43.2(4) ms	β− (78%)		3/2+
						β−n (22(3)%)
						β−2n ?	?
	11	19	30.009098(5)	1969	45.9(7) ms	β− (70.2(2.2)%)		2+
						β−n (28.6(2.2)%)
						β−2n (1.24(19)%)
						β−α (5.5(2)%×10−5)
	11	20	31.013147(15)	1969	16.8(3) ms	β− (> 63.2(3.5)%)		3/2+
						β−n (36.0(3.5)%)
						β−2n (0.73(9)%)
						β−3n (< 0.05%)
	11	21	32.020010(40)	1972	12.9(3) ms	β− (66.4(6.2)%)		(3−)
						β−n (26(6)%)
						β−2n (7.6(1.5)%)
	625 keV			2023	24(2) μs	IT		(0+,6−)
	11	22	33.02553(48)	1972	8.2(4) ms	β−n (47(6)%)		(3/2+)
						β− (40.0(6.7)%)
						β−2n (13(3)%)
	11	23	34.03401(64)	1983	5.5(1.0) ms	β−2n (~50%)		1+
						β− (~35%)
						β−n (~15%)
	11	24	35.04061(72)#	1983	1.5(5) ms	β−		3/2+#
						β−n ?	?
						β−2n ?	?
	11	26	37.05704(74)#	2002	1# ms [> 1.5 μs]	β− ?	?	3/2+#
						β−n ?	?
						β−2n ?	?
	11	28	39.07512(80)#	2022	1# ms [> 400 ns]	β− ?	?	3/2+#
						β−n ?	?
						β−2n ?	?

Sodium-22

File:Sodium-22, 1-microcurie disk.jpg

Disk containing 1 μCi of sodium-22

Sodium-22 is a radioactive isotope of sodium, undergoing positron emission to ²²Ne with a half-life of 2.6019 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 the sole natural isotope of sodium, with an atomic mass of 22.98976928. Because of this, sodium-23 is used in 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 is generally created from common sodium-23 by neutron activation. With a half-life of 14.956 hours, ²⁴Na decays to ²⁴Mg by emission of an electron and, almost always, 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 medical treatment required.

When sodium is used as coolant in fast breeder reactors, radioactive ²⁴Na is created within the coolant. When the ²⁴Na decays, magnesium forms and builds up 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 placed within the 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.

See also

Daughter products other than sodium

• Isotopes of magnesium
• Isotopes of neon
• Isotopes of oxygen

External links

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