Chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
(
17Cl) has 25 isotopes with mass numbers ranging from
28Cl to
52Cl and 2
isomers
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers.
...
(
34mCl and
38mCl). There are two stable
isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...
s,
35Cl (75.77%) and
37Cl (24.23%), giving chlorine a
standard atomic weight of 35.45. 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, with half-lives less than 10 picoseconds and 30 nanoseconds, respectively—the half-life of
28Cl is unknown.
List of isotopes
, -
,
28Cl
, style="text-align:right" , 17
, style="text-align:right" , 11
, 28.02954(64)#
,
,
p
,
27S
, 1+#
,
,
, -
,
29Cl
, style="text-align:right" , 17
, style="text-align:right" , 12
, 29.01413(20)
, <10 ps
, p
,
28S
, (1/2+)
,
,
, -
,
30Cl
, style="text-align:right" , 17
, style="text-align:right" , 13
, 30.00477(21)#
, <30 ns
, p
,
29S
, 3+#
,
,
, -
, rowspan=2,
31Cl
, rowspan=2 style="text-align:right" , 17
, rowspan=2 style="text-align:right" , 14
, rowspan=2, 30.992448(4)
, rowspan=2, 190(1) ms
,
β+ (97.6%)
,
31S
, rowspan=2, 3/2+
, rowspan=2,
, rowspan=2,
, -
, β
+, p (2.4%)
,
30P
, -
, rowspan=3,
32Cl
, rowspan=3 style="text-align:right" , 17
, rowspan=3 style="text-align:right" , 15
, rowspan=3, 31.9856846(6)
, rowspan=3, 298(1) ms
, β
+ (99.92%)
,
32S
, rowspan=3, 1+
, rowspan=3,
, rowspan=3,
, -
, β
+,
α (.054%)
,
28Si
, -
, β
+, p (.026%)
,
31P
, -
,
33Cl
, style="text-align:right" , 17
, style="text-align:right" , 16
, 32.9774520(4)
, 2.5038(22) s
, β
+
,
33S
, 3/2+
,
,
, -
,
34Cl
, style="text-align:right" , 17
, style="text-align:right" , 17
, 33.97376249(5)
, 1.5266(4) s
, β
+
,
34S
, 0+
,
,
, -
, rowspan=2 style="text-indent:1em" ,
34mCl
, rowspan=2 colspan="3" style="text-indent:2em" , 146.360(27) keV
, rowspan=2, 31.99(3) min
, β
+ (55.4%)
,
34S
, rowspan=2, 3+
, rowspan=2,
, rowspan=2,
, -
,
IT (44.6%)
,
34Cl
, -
,
35Cl
, style="text-align:right" , 17
, style="text-align:right" , 18
, 34.96885269(4)
, colspan=3 align=center, Stable
, 3/2+
, 0.7576(10)
, 0.75644–0.75923
, -
, rowspan=2,
36Cl[Used in ]radiodating
Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares ...
water
, rowspan=2 style="text-align:right" , 17
, rowspan=2 style="text-align:right" , 19
, rowspan=2, 35.96830682(4)
, rowspan=2, 3.013(15)×10
5 y
, β
− (98.1%)
,
36Ar
, rowspan=2, 2+
, rowspan=2, Trace
Cosmogenic nuclide
Cosmogenic nuclides (or cosmogenic isotopes) are rare nuclides (isotopes) created when a high-energy cosmic ray interacts with the nucleus of an '' in situ'' Solar System atom, causing nucleons (protons and neutrons) to be expelled from the atom ...
, rowspan=2, approx. 7×10
−13
, -
, β
+ (1.9%)
,
36S
, -
,
37Cl
, style="text-align:right" , 17
, style="text-align:right" , 20
, 36.96590258(6)
, colspan=3 align=center, Stable
, 3/2+
, 0.2424(10)
, 0.24077–0.24356
, -
,
38Cl
, style="text-align:right" , 17
, style="text-align:right" , 21
, 37.96801042(11)
, 37.24(5) min
, β
−
,
38Ar
, 2−
,
,
, -
, style="text-indent:1em" ,
38mCl
, colspan="3" style="text-indent:2em" , 671.365(8) keV
, 715(3) ms
, IT
,
38Cl
, 5−
,
,
, -
,
39Cl
, style="text-align:right" , 17
, style="text-align:right" , 22
, 38.9680082(19)
, 56.2(6) min
, β
−
,
39Ar
, 3/2+
,
,
, -
,
40Cl
, style="text-align:right" , 17
, style="text-align:right" , 23
, 39.97042(3)
, 1.35(2) min
, β
−
,
40Ar
, 2−
,
,
, -
,
41Cl
, style="text-align:right" , 17
, style="text-align:right" , 24
, 40.97068(7)
, 38.4(8) s
, β
−
,
41Ar
, (1/2+,3/2+)
,
,
, -
,
42Cl
, style="text-align:right" , 17
, style="text-align:right" , 25
, 41.97334(6)
, 6.8(3) s
, β
−
,
42Ar
,
,
,
, -
, rowspan=2,
43Cl
, rowspan=2 style="text-align:right" , 17
, rowspan=2 style="text-align:right" , 26
, rowspan=2, 42.97406(7)
, rowspan=2, 3.13(9) s
, β
− (>99.9%)
,
43Ar
, rowspan=2, (3/2+)
, rowspan=2,
, rowspan=2,
, -
, β
−,
n (<.1%)
,
42Ar
, -
, rowspan=2,
44Cl
, rowspan=2 style="text-align:right" , 17
, rowspan=2 style="text-align:right" , 27
, rowspan=2, 43.97812(15)
, rowspan=2, 0.56(11) s
, β
− (92%)
,
44Ar
, rowspan=2, (2-)
, rowspan=2,
, rowspan=2,
, -
, β
−, n (8%)
,
43Ar
, -
, rowspan=2,
45Cl
, rowspan=2 style="text-align:right" , 17
, rowspan=2 style="text-align:right" , 28
, rowspan=2, 44.98039(15)
, rowspan=2, 413(25) ms
, β
− (76%)
,
45Ar
, rowspan=2, (3/2+)
, rowspan=2,
, rowspan=2,
, -
, β
−, n (24%)
,
44Ar
, -
, rowspan=2,
46Cl
, rowspan=2 style="text-align:right" , 17
, rowspan=2 style="text-align:right" , 29
, rowspan=2, 45.98512(22)
, rowspan=2, 232(2) ms
, β
−, n (60%)
,
45Ar
, rowspan=2, 2-#
, rowspan=2,
, rowspan=2,
, -
, β
− (40%)
,
46Ar
, -
, rowspan=2,
47Cl
, rowspan=2 style="text-align:right" , 17
, rowspan=2 style="text-align:right" , 30
, rowspan=2, 46.98950(43)#
, rowspan=2, 101(6) ms
, β
− (97%)
,
47Ar
, rowspan=2, 3/2+#
, rowspan=2,
, rowspan=2,
, -
, β
−, n (3%)
,
46Ar
, -
,
48Cl
, style="text-align:right" , 17
, style="text-align:right" , 31
, 47.99541(54)#
, 100# ms
200 ns, β
−
,
48Ar
,
,
,
, -
,
49Cl
, style="text-align:right" , 17
, style="text-align:right" , 32
, 49.00101(64)#
, 50# ms
200 ns, β
−
,
49Ar
, 3/2+#
,
,
, -
,
50Cl
, style="text-align:right" , 17
, style="text-align:right" , 33
, 50.00831(64)#
, 20# ms
, β
−
,
50Ar
,
,
,
, -
,
51Cl
, style="text-align:right" , 17
, style="text-align:right" , 34
, 51.01534(75)#
, 2# ms
200 ns, β
−
,
51Ar
, 3/2+#
,
,
, -
,
52Cl
, style="text-align:right" , 17
, style="text-align:right" , 35
,
,
, β
−
,
52Ar
,
,
,
Chlorine-36
Trace amounts of
radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...
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 of
36 Ar by interactions with
cosmic ray
Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...
protons. In the subsurface environment,
36Cl is generated primarily as a result of
neutron capture
Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, ...
by
35Cl or
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.
Muon capture by heavy nuclei often leads to emission of particles; most often neutrons, but c ...
by
40 Ca.
36Cl decays to either
36 S (1.9%) or to
36 Ar (98.1%), with a combined
half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...
of 308,000 years. The half-life of this
hydrophilic
A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press.
In contrast, hydrophobes are ...
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 neutron irradiation of
seawater
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appr ...
during atmospheric detonations of
nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...
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, also commonly referred to as earth or dirt
Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty.
Common types of dirt include:
* Debri ...
and
ground water
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
,
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. In chloride-based
molten salt reactor
A molten salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a molten salt mixture. Only two MSRs have ever operated, both research reactors in the United States. The 1950's ...
s the production of by
neutron capture
Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, ...
is an inevitable consequence of using natural isotope mixtures of chlorine (i.e. Those containing ). This produces a long lived radioactive product which has to be stored or disposed off.
Isotope separation
Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes. The use of the nuclides produced is varied. The largest variety is used in research (e.g. in chemistry where atoms of "marker" n ...
to produce pure can vastly reduce production, but a small amount might still be produced by (n,2n) reactions involving
fast neutron
The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with ...
s.
Chlorine-37
Stable chlorine-37 makes up about 24.23% of the naturally occurring chlorine on earth. Variation occurs as chloride mineral deposits have a slightly elevated chlorine-37 balance over the average found in sea water and
halite
Halite (), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, p ...
deposits.
References
External links
Chlorine isotopes data from ''The Berkeley Laboratory Isotopes Project's''
{{Navbox element isotopes
Chlorine
Chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...