Isotopes of sodium
Encyclopedia
There are twenty recognized isotope
s of sodium
ranging from 18Na to 37Na and two isomer
s (22mNa and 24mNa). 23Na is the only stable (and the only primordial) isotope. As such, it is considered a monoisotopic element and it has a standard atomic mass: 22.98976928(2) u. Sodium has two radioactive cosmogenic isotopes (22Na, half-life
= 2.605 years; and 24Na
, half-life ≈ 15 hours). With the exception of those two, all other isotopes have half-lives under a minute, most under a second. The least stable is 18Na, with a half-life of 1.3*10-21 (4) seconds.
Acute neutron radiation exposure (e.g., from a nuclear criticality accident
) converts some of the stable 23Na 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
.
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s of sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
ranging from 18Na to 37Na and two isomer
Nuclear isomer
A nuclear isomer is a metastable state of an atomic nucleus caused by the excitation of one or more of its nucleons . "Metastable" refers to the fact that these excited states have half-lives more than 100 to 1000 times the half-lives of the other possible excited nuclear states...
s (22mNa and 24mNa). 23Na is the only stable (and the only primordial) isotope. As such, it is considered a monoisotopic element and it has a standard atomic mass: 22.98976928(2) u. Sodium has two radioactive cosmogenic isotopes (22Na, half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
= 2.605 years; and 24Na
Sodium-24
Sodium-24 is one of the more important isotopes of sodium. It is radioactive and created from common sodium-23 by neutron bombardment. With a 15-hour half-life, 24Na decays to 24Mg by emission of an electron and two gamma rays. Exposure of the human body to intense neutron flux creates 24Na in...
, half-life ≈ 15 hours). With the exception of those two, all other isotopes have half-lives under a minute, most under a second. The least stable is 18Na, with a half-life of 1.3*10-21 (4) seconds.
Acute neutron radiation exposure (e.g., from a nuclear criticality accident
Criticality accident
A criticality accident, sometimes referred to as an excursion or a power excursion, is an accidental increase of nuclear chain reactions in a fissile material, such as enriched uranium or plutonium...
) converts some of the stable 23Na 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
Positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1e, a spin of ½, and has the same mass as an electron...
-emitting isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
with a remarkably long half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
. It is used to create test-objects and point-sources for Positron emission tomography
Positron emission tomography
Positron emission tomography is nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide , which is introduced into the body on a...
.
Table
| nuclide symbol |
Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... ) |
N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... ) |
isotopic mass (u) |
half-life | decay mode(s)Abbreviations: IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
daughter isotope(s)Bold for stable isotopes |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
|---|---|---|---|---|---|---|---|---|---|
| excitation energy | |||||||||
| 18Na | 11 | 7 | 18.02597(5) | 1.3(4)×10−21 s | p Proton emission Proton emission is a type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state of very... (>99.9%) |
17Ne | (1-)# | ||
| β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... (<.1%) |
18Ne | ||||||||
| 19Na | 11 | 8 | 19.013877(13) | <40 ns | p | 18Ne | (5/2+)# | ||
| 20Na | 11 | 9 | 20.007351(7) | 447.9(23) ms | β+ (75%) | 20Ne | 2+ | ||
| β+, α Alpha decay Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less... (25%) |
16O | ||||||||
| 21Na | 11 | 10 | 20.9976552(8) | 22.49(4) s | β+ | 21Ne | 3/2+ | ||
| 22Na | 11 | 11 | 21.9944364(4) | 2.6027(10) yr | β+ | 22Ne | 3+ | TraceCosmogenic nuclide | |
| 22mNa | 583.03(9) keV | 244(6) ns | 1+ | ||||||
| 23Na | 11 | 12 | 22.9897692809(29) | Stable | 3/2+ | 1.0000 | |||
| 24Na Sodium-24 Sodium-24 is one of the more important isotopes of sodium. It is radioactive and created from common sodium-23 by neutron bombardment. With a 15-hour half-life, 24Na decays to 24Mg by emission of an electron and two gamma rays. Exposure of the human body to intense neutron flux creates 24Na in... |
11 | 13 | 23.99096278(8) | 14.9590(12) h | β- | 24Mg | 4+ | Trace | |
| 24mNa | 472.207(9) keV | 20.20(7) ms | IT Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... (99.95%) |
24Na | 1+ | ||||
| β− (.05%) | 24Mg | ||||||||
| 25Na | 11 | 14 | 24.9899540(13) | 59.1(6) s | β− | 25Mg | 5/2+ | ||
| 26Na | 11 | 15 | 25.992633(6) | 1.077(5) s | β− | 26Mg | 3+ | ||
| 27Na | 11 | 16 | 26.994077(4) | 301(6) ms | β− (99.87%) | 27Mg | 5/2+ | ||
| β−, n Neutron emission Neutron emission is a type of radioactive decay of atoms containing excess neutrons, in which a neutron is simply ejected from the nucleus. Two examples of isotopes which emit neutrons are helium-5 and beryllium-13... (.13%) |
26Mg | ||||||||
| 28Na | 11 | 17 | 27.998938(14) | 30.5(4) ms | β− (99.421%) | 28Mg | 1+ | ||
| β−, n (.579%) | 27Mg | ||||||||
| 29Na | 11 | 18 | 29.002861(14) | 44.9(12) ms | β− (74.09%) | 29Mg | 3/2(+#) | ||
| β−, n (25.91%) | 28Mg | ||||||||
| 30Na | 11 | 19 | 30.008976(27) | 48.4(17) ms | β− (68.83%) | 30Mg | 2+ | ||
| β−, n (30.0%) | 29Mg | ||||||||
| β−, 2n (1.17%) | 28Mg | ||||||||
| β−, α | 26Ne | ||||||||
| 31Na | 11 | 20 | 31.01359(23) | 17.0(4) ms | β− (62.05%) | 31Mg | (3/2+) | ||
| β−, n | 30Mg | ||||||||
| β−, 2n | 29Mg | ||||||||
| β−, 3n | 28Mg | ||||||||
| 32Na | 11 | 21 | 32.02047(38) | 12.9(7) ms | β− | 32Mg | (3-,4-) | ||
| β−, n | 31Mg | ||||||||
| β−, 2n | 30Mg | ||||||||
| 33Na | 11 | 22 | 33.02672(94) | 8.2(2) ms | β−, n (52.0%) | 32Mg | 3/2+# | ||
| β− (36.0%) | 33Mg | ||||||||
| β−, 2n (12.0%) | 31Mg | ||||||||
| 34Na | 11 | 23 | 34.03517(96)# | 5.5(10) ms | β−, 2n (50.0%) | 32Mg | 1+ | ||
| β− (35.0%) | 34Mg | ||||||||
| β−, n (15.0%) | 33Mg | ||||||||
| 35Na | 11 | 24 | 35.04249(102)# | 1.5(5) ms | β− (>99.9%) | 35Mg | 3/2+# | ||
| β−, n (<.1%) | 34Mg | ||||||||
| 36Na | 11 | 25 | 36.05148(102)# | <260 ns | |||||
| 37Na | 11 | 26 | 37.05934(103)# | 1# ms [>1.5 µs] | 3/2+# | ||||