Isotopes of chlorine
Encyclopedia
Chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

(Cl) has 24 isotopes with mass numbers ranging from 28Cl to 51Cl and 2 isomers (34mCl and 38mCl). There are two principal stable 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, 35Cl (75.78%) and 37Cl (24.22%), found in the relative proportions of 37.89:12.11, not 3:1, respectively, giving chlorine a standard atomic mass of 35.453, not 35.5. The longest-lived radioactive isotope is 36Cl which has a half-life of 301,000 years. All other isotopes have half-lives under 1 hour, many less than one second. The shortest-lived are 29Cl and 30Cl, wiith half-lives less than 20 and 30 nanoseconds, respectively—the half-life of 28Cl is unknown.

Standard atomic mass: 35.453(2) u

Chlorine-36 (36Cl)

Trace amounts of radioactive 36Cl exist in the environment, in a ratio of about 7×10−13 to 1 with stable isotopes. 36Cl is produced in the atmosphere by spallation
Spallation
In general, spallation is a process in which fragments of material are ejected from a body due to impact or stress. In the context of impact mechanics it describes ejection or vaporization of material from a target during impact by a projectile...

 of 36Ar
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...

 by interactions with cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

 proton
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....

s. In the subsurface environment, 36Cl is generated primarily as a result of neutron capture
Neutron capture
Neutron capture is a kind of nuclear reaction in which an atomic nucleus collides with one or more neutrons and they merge to form a heavier nucleus. Since neutrons have no electric charge they can enter a nucleus more easily than positively charged protons, which are repelled...

 by 35Cl or muon capture
Muon capture
Muon capture is the capture of a negative muon by a proton, usually resulting in production of a neutron and a neutrino, and sometimes a gamma photon....

 by 40Ca
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

. 36Cl decays to 36S
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 (1.9%) and to 36Ar
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...

 (98.1%), with a combined 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 308,000 years. The half-life of this hydrophilic nonreactive isotope makes it suitable for geologic dating in the range of 60,000 to 1 million years. Additionally, large amounts of 36Cl were produced by irradiation of seawater
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

 during atmospheric detonations of 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 between 1952 and 1958. The residence time of 36Cl in the atmosphere is about 1 week. Thus, as an event marker of 1950s water in soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 and ground water, 36Cl is also useful for dating waters less than 50 years before the present. 36Cl has seen use in other areas of the geological sciences, forecasts, and elements.

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
28Cl 17 11 28.02851(54)# 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...

27S (1+)#
29Cl 17 12 29.01411(21)# <20 ns p 28S (3/2+)#
30Cl 17 13 30.00477(21)# <30 ns p 29S (3+)#
31Cl 17 14 30.99241(5) 150(25) 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...

 (99.3%)
31S 3/2+
β+, p (.7%) 30P
32Cl 17 15 31.985690(7) 298(1) ms β+ (99.92%) 32S 1+
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...

 (.054%)
28Al
β+, p (.026%) 31P
33Cl 17 16 32.9774519(5) 2.511(3) s β+ 33S 3/2+
34Cl 17 17 33.97376282(19) 1.5264(14) s β+ 34S 0+
34mCl 146.36(3) keV 32.00(4) min β+ (55.4%) 34S 3+
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....

 (44.6%)
34Cl
35Cl 17 18 34.96885268(4) Stable 3/2+ 0.7576(10) 0.75644-0.75923
36Cl
Chlorine-36
Chlorine-36 is an isotope of chlorine. Chlorine has two stable isotopes and one radioactive environmental isotope: the cosmogenic isotope 36Cl. The ratio of 36Cl to stable 37Cl in the environment is ~700 × 10−15. Its half-life is 301,000 ± 4,000 years. The long half-life of 36Cl makes it...

Used in radiodating water
17 19 35.96830698(8) 3.01(2)×105 y β- (98.1%) 36Ar 2+ TraceCosmogenic nuclide
Cosmogenic nuclide
See also Environmental radioactivity#NaturalCosmogenic nuclides are rare isotopes created when a high-energy cosmic ray interacts with the nucleus of an in situ solar system atom, causing cosmic ray spallation...

approx. 7*10-13
ε (1.9%) 36S
37Cl
Chlorine-37
Chlorine-37, or ', is one of the stable isotopes of chlorine, the other being chlorine-35 . Its nucleus contains 17 protons and 20 neutrons for a total of 37 nucleons...

17 20 36.96590259(5) Stable 3/2+ 0.2424(10) 0.24077-0.24356
38Cl 17 21 37.96801043(10) 37.24(5) min β- 38Ar 2-
38mCl 671.361(8) keV 715(3) ms IT 38Cl 5-
39Cl 17 22 38.9680082(19) 55.6(2) min β- 39Ar 3/2+
40Cl 17 23 39.97042(3) 1.35(2) min β- 40Ar 2-
41Cl 17 24 40.97068(7) 38.4(8) s β- 41Ar (1/2+,3/2+)
42Cl 17 25 41.97325(15) 6.8(3) s β- 42Ar
43Cl 17 26 42.97405(17) 3.07(7) s β- (>99.9%) 43Ar 3/2+#
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...

(<.1%)
42Ar
44Cl 17 27 43.97828(12) 0.56(11) s β- (92%) 44Ar
β-, n (8%) 43Ar
45Cl 17 28 44.98029(13) 400(40) ms β- (76%) 45Ar 3/2+#
β-, n (24%) 44Ar
46Cl 17 29 45.98421(77) 232(2) ms β-, n (60%) 45Ar
β- (40%) 46Ar
47Cl 17 30 46.98871(64)# 101(6) ms β- (97%) 47Ar 3/2+#
β-, n (3%) 46Ar
48Cl 17 31 47.99495(75)# 100# ms [>200 ns] β- 48Ar
49Cl 17 32 49.00032(86)# 50# ms [>200 ns] β- 49Ar 3/2+#
50Cl 17 33 50.00784(97)# 20# ms β- 50Ar
51Cl 17 34 51.01449(107)# 2# ms [>200 ns] β- 51Ar 3/2+#



External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK