View source for Isotopes of chlorine



'''[[Chlorine]]''' ('''Cl''') has isotopes with mass numbers ranging from 32 g mol<sup>−1</sup> to 40 g mol<sup>−1</sup>. There are two principal stable [[isotope]]s, <sup>35</sup>Cl (75.77%) and <sup>37</sup>Cl (24.23%), found in the relative proportions of 3:1 respectively, giving chlorine [[atom]]s in bulk an apparent atomic weight of 35.5.
<br />Standard atomic mass: 35.453(2) [[unified atomic mass unit|u]]

==Chlorine-36 (<sup>36</sup>Cl)==
{{main|Chlorine-36}}
Trace amounts of [[radioactive]] <sup>36</sup>Cl exist in the environment, in a ratio of about 7x10<sup>−13</sup> to 1 with stable isotopes. <sup>36</sup>Cl is produced in the atmosphere by [[spallation]] of <sup>36</sup>[[argon|Ar]] by interactions with [[cosmic ray]] [[proton]]s. In the subsurface environment, <sup>36</sup>Cl is generated primarily as a result of [[neutron capture]] by <sup>35</sup>Cl or [[muon capture]] by <sup>40</sup>[[calcium|Ca]]. <sup>36</sup>Cl decays to <sup>36</sup>[[sulfur|S]] and to <sup>36</sup>[[argon|Ar]], with a combined [[half-life]] 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 <sup>36</sup>Cl were produced by irradiation of [[seawater]] during atmospheric detonations of [[nuclear weapon]]s between 1952 and 1958. The residence time of <sup>36</sup>Cl in the atmosphere is about 1 week. Thus, as an event marker of 1950s water in [[soil]] and [[ground water]], <sup>36</sup>Cl is also useful for dating waters less than 50 years before the present. <sup>36</sup>Cl has seen use in other areas of the geological sciences, including dating ice and sediments.


== Table ==
{| class="wikitable" style="font-size:95%; white-space:nowrap"
! rowspan="2" | nuclide<br />symbol
! Z([[proton|p]])
! N([[neutron|n]])
! &nbsp;<br />isotopic mass (u)<br />&nbsp;
! rowspan="2" | half-life
! rowspan="2" | nuclear<br />spin
! rowspan="2" | representative<br />isotopic<br />composition<br />(mole fraction)
! rowspan="2" | range of natural<br />variation<br />(mole fraction)
|-
! colspan="3" | excitation energy
|-
| <sup>28</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 11
| 28.02851(54)#
|
| (1+)#
|
|
|-
| <sup>29</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 12
| 29.01411(21)#
| <20 ns
| (3/2+)#
|
|
|-
| <sup>30</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 13
| 30.00477(21)#
| <30 ns
| (3+)#
|
|
|-
| <sup>31</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 14
| 30.99241(5)
| 150(25) ms
| 3/2+
|
|
|-
| <sup>32</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 15
| 31.985690(7)
| 298(1) ms
| 1+
|
|
|-
| <sup>33</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 16
| 32.9774519(5)
| 2.511(3) s
| 3/2+
|
|
|-
| <sup>34</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 17
| 33.97376282(19)
| 1.5264(14) s
| 0+
|
|
|-
| style="text-indent:1em" | <sup>34m</sup>Cl
| colspan="3" style="text-indent:2em" | 146.36(3) keV
| 32.00(4) min
| 3+
|
|
|-
| <sup>35</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 18
| 34.96885268(4)
| STABLE
| 3/2+
| 0.7576(10)
| 0.75644-0.75923
|-
| [[Chlorine-36|<sup>36</sup>Cl]]
| style="text-align:right" | 17
| style="text-align:right" | 19
| 35.96830698(8)
| 3.01(2)E+5 a
| 2+
|
|
|-
| <sup>37</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 20
| 36.96590259(5)
| STABLE
| 3/2+
| 0.2424(10)
| 0.24077-0.24356
|-
| <sup>38</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 21
| 37.96801043(10)
| 37.24(5) min
| 2-
|
|
|-
| style="text-indent:1em" | <sup>38m</sup>Cl
| colspan="3" style="text-indent:2em" | 671.361(8) keV
| 715(3) ms
| 5-
|
|
|-
| <sup>39</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 22
| 38.9680082(19)
| 55.6(2) min
| 3/2+
|
|
|-
| <sup>40</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 23
| 39.97042(3)
| 1.35(2) min
| 2-
|
|
|-
| <sup>41</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 24
| 40.97068(7)
| 38.4(8) s
| (1/2+,3/2+)
|
|
|-
| <sup>42</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 25
| 41.97325(15)
| 6.8(3) s
|
|
|
|-
| <sup>43</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 26
| 42.97405(17)
| 3.07(7) s
| 3/2+#
|
|
|-
| <sup>44</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 27
| 43.97828(12)
| 0.56(11) s
|
|
|
|-
| <sup>45</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 28
| 44.98029(13)
| 400(40) ms
| 3/2+#
|
|
|-
| <sup>46</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 29
| 45.98421(77)
| 232(2) ms
|
|
|
|-
| <sup>47</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 30
| 46.98871(64)#
| 101(6) ms
| 3/2+#
|
|
|-
| <sup>48</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 31
| 47.99495(75)#
| 100# ms [>200 ns]
|
|
|
|-
| <sup>49</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 32
| 49.00032(86)#
| 50# ms [>200 ns]
| 3/2+#
|
|
|-
| <sup>50</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 33
| 50.00784(97)#
| 20# ms
|
|
|
|-
| <sup>51</sup>Cl
| style="text-align:right" | 17
| style="text-align:right" | 34
| 51.01449(107)#
| 2# ms [>200 ns]
| 3/2+#
|
|
|}

=== Notes ===
* Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
* Commercially available materials may have been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations from the given mass and composition can occur.
* Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
* Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

== References ==
* Isotope masses from [http://www.nndc.bnl.gov/amdc/index.html Ame2003 Atomic Mass Evaluation] by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in ''Nuclear Physics'' A729 (2003).
* Isotopic compositions and standard atomic masses from [http://www.iupac.org/publications/pac/2003/7506/7506x0683.html Atomic weights of the elements. Review 2000 (IUPAC Technical Report)]. ''Pure Appl. Chem.'' Vol. 75, No. 6, pp. 683-800, (2003) and [http://www.iupac.org/news/archives/2005/atomic-weights_revised05.html Atomic Weights Revised (2005)].
* Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
** Audi, Bersillon, Blachot, Wapstra. [http://amdc.in2p3.fr/web/nubase_en.html The Nubase2003 evaluation of nuclear and decay properties], Nuc. Phys. A 729, pp. 3-128 (2003).
** National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the [http://www.nndc.bnl.gov/nudat2/ NuDat 2.1 database] (retrieved Sept. 2005).
** David R. Lide (ed.), Norman E. Holden in ''CRC Handbook of Chemistry and Physics, 85th Edition'', online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.

==External links==
*[http://ie.lbl.gov/education/parent/Cl_iso.htm Chlorine isotopes data from ''The Berkeley Laboratory Isotopes Project's'']

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