Isotopes of arsenic
Encyclopedia
Arsenic
(As) has 33 known isotope
s and at least 10 isomers
. Only one of these isotopes, 75As, is stable; as such, it is considered a monoisotopic
element. The longest-lived radioisotope is 73As has a half-life of 80 days. Arsenic has been proposed as a "salting
" material for nuclear weapon
s (cobalt
is another, better-known salting material). A jacket of 75As, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope 76As with a half-life
of 1.0778 days and produce approximately 1.13 MeV
of gamma radiation
, significantly increasing the radioactivity of the weapon's fallout
for several hours. Such a weapon is not known to have ever been built, tested, or used.
Standard atomic mass: 74.92160(2) u.
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
(As) has 33 known 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...
s and at least 10 isomers
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...
. Only one of these isotopes, 75As, is stable; as such, it is considered a monoisotopic
Monoisotopic
* Monoisotopic mass is a term from mass spectrometry, and usually refers to the atomic weight of a molecule calculated using the atomic weight of the most naturally abundant isotope of that element....
element. The longest-lived radioisotope is 73As has a half-life of 80 days. Arsenic has been proposed as a "salting
Salted bomb
A salted bomb is a variation of a nuclear weapon designed to produce enhanced quantities of radioactive fallout, rendering a large area uninhabitable...
" material for nuclear weapon
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...
s (cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
is another, better-known salting material). A jacket of 75As, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope 76As with a 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...
of 1.0778 days and produce approximately 1.13 MeV
MEV
MeV and meV are multiples and submultiples of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:In entertainment:* Musica Elettronica Viva, an Italian musical group...
of gamma radiation
Gamma ray
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...
, significantly increasing the radioactivity of the weapon's fallout
Nuclear fallout
Fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and shock wave have passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes...
for several hours. Such a weapon is not known to have ever been built, tested, or used.
Standard atomic mass: 74.92160(2) u.
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: EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... |
daughter isotope(s)Bold for stable isotopes, bold italic for nearly-stable isotopes (half-life longer than the age of the universe Age of the universe The age of the universe is the time elapsed since the Big Bang posited by the most widely accepted scientific model of cosmology. The best current estimate of the age of the universe is 13.75 ± 0.13 billion years within the Lambda-CDM concordance model... ) |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
|---|---|---|---|---|---|---|---|---|---|
| excitation energy | |||||||||
| 60As | 33 | 27 | 59.99313(64)# | p Proton decay In particle physics, proton decay is a hypothetical form of radioactive decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron... |
59Ge | 5+# | |||
| 61As | 33 | 28 | 60.98062(64)# | p | 60Ge | 3/2-# | |||
| 62As | 33 | 29 | 61.97320(32)# | p | 61Ge | 1+# | |||
| 63As | 33 | 30 | 62.96369(54)# | p | 62Ge | (3/2-)# | |||
| 64As | 33 | 31 | 63.95757(38)# | 40(30) ms [18(+43-7) ms] |
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... |
64Ge | 0+# | ||
| 65As | 33 | 32 | 64.94956(32)# | 170(30) ms | β+ | 65Ge | 3/2-# | ||
| 66As | 33 | 33 | 65.94471(73) | 95.77(23) ms | β+ | 66Ge | (0+) | ||
| 66m1As | 1356.70(17) keV | 1.1(1) µs | (5+) | ||||||
| 66m2As | 3023.9(3) keV | 8.2(5) µs | (9+) | ||||||
| 67As | 33 | 34 | 66.93919(11) | 42.5(12) s | β+ | 67Ge | (5/2-) | ||
| 68As | 33 | 35 | 67.93677(5) | 151.6(8) s | β+ | 68Ge | 3+ | ||
| 68mAs | 425.21(16) keV | 111(20) s [?107(+23-16) ns] |
1+ | ||||||
| 69As | 33 | 36 | 68.93227(3) | 15.2(2) min | β+ | 69Ge | 5/2- | ||
| 70As | 33 | 37 | 69.93092(5) | 52.6(3) min | β+ | 70Ge | 4(+#) | ||
| 70mAs | 32.008(23) keV | 96(3) µs | 2(+) | ||||||
| 71As | 33 | 38 | 70.927112(5) | 65.28(15) h | β+ | 71Ge | 5/2- | ||
| 72As | 33 | 39 | 71.926752(5) | 26.0(1) h | β+ | 72Ge | 2- | ||
| 73As | 33 | 40 | 72.923825(4) | 80.30(6) d | EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... |
73Ge | 3/2- | ||
| 74As | 33 | 41 | 73.9239287(25) | 17.77(2) d | β+ (66%) | 74Ge | 2- | ||
| β- (34%) | 74Se | ||||||||
| 75As | 33 | 42 | 74.9215965(20) | Stable | 3/2- | 1.0000 | |||
| 75mAs | 303.9241(7) keV | 17.62(23) ms | 9/2+ | ||||||
| 76As | 33 | 43 | 75.922394(2) | 1.0942(7) d | β- (99.98%) | 76Se | 2- | ||
| EC (.02%) | 76Ge | ||||||||
| 76mAs | 44.425(1) keV | 1.84(6) µs | (1)+ | ||||||
| 77As | 33 | 44 | 76.9206473(25) | 38.83(5) h | β- | 77mSe | 3/2- | ||
| 77mAs | 475.443(16) keV | 114.0(25) µs | 9/2+ | ||||||
| 78As | 33 | 45 | 77.921827(11) | 90.7(2) min | β- | 78Se | 2- | ||
| 79As | 33 | 46 | 78.920948(6) | 9.01(15) min | β- | 79mSe | 3/2- | ||
| 79mAs | 772.81(6) keV | 1.21(1) µs | (9/2)+ | ||||||
| 80As | 33 | 47 | 79.922534(25) | 15.2(2) s | β- | 80Se | 1+ | ||
| 81As | 33 | 48 | 80.922132(6) | 33.3(8) s | β- | 81mSe | 3/2- | ||
| 82As | 33 | 49 | 81.92450(21) | 19.1(5) s | β- | 82Se | (1+) | ||
| 82mAs | 250(200) keV | 13.6(4) s | β- | 82Se | (5-) | ||||
| 83As | 33 | 50 | 82.92498(24) | 13.4(3) s | β- | 83mSe | 3/2-# | ||
| 84As | 33 | 51 | 83.92906(32)# | 4.02(3) s | β- (99.721%) | 84Se | (3)(+#) | ||
| 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... (.029%) |
83Se | ||||||||
| 84mAs | 0(100)# keV | 650(150) ms | |||||||
| 85As | 33 | 52 | 84.93202(21)# | 2.021(10) s | β-, n (59.4%) | 84Se | (3/2-)# | ||
| β- (40.6%) | 85Se | ||||||||
| 86As | 33 | 53 | 85.93650(32)# | 0.945(8) s | β- (67%) | 86Se | |||
| β-, n (33%) | 85Se | ||||||||
| 87As | 33 | 54 | 86.93990(32)# | 0.56(8) s | β- (84.6%) | 87Se | 3/2-# | ||
| β-, n (15.4%) | 86Se | ||||||||
| 88As | 33 | 55 | 87.94494(54)# | 300# ms [>300 ns] |
β- | 88Se | |||
| β-, n | 87Se | ||||||||
| 89As | 33 | 56 | 88.94939(54)# | 200# ms [>300 ns] |
β- | 89Se | 3/2-# | ||
| 90As | 33 | 57 | 89.95550(86)# | 80# ms [>300 ns] |
|||||
| 91As | 33 | 58 | 90.96043(97)# | 50# ms [>300 ns] |
3/2-# | ||||
| 92As | 33 | 59 | 91.96680(97)# | 30# ms [>300 ns] |
|||||