View source for Isotopes of lithium



==Overview==
Naturally occurring '''[[lithium]]''' ('''Li''') (standard atomic mass: 6.941(2) [[unified atomic mass unit|u]]) is composed of two stable [[isotope]]s ({{SimpleNuclide|Lithium|6}} and {{SimpleNuclide|Lithium|7}}, the latter being the more abundant (92.5% [[natural abundance]]). Seven [[radioisotope]]s have been characterized, the most stable being {{SimpleNuclide|Lithium|8}} with a [[half-life]] of {{val|838|u=ms}} and {{SimpleNuclide|Lithium|9}} with a half-life of {{val|178.3|u=ms}}. All of the remaining [[radioactive]] isotopes have half-lives that are shorter than {{val|8.6|u=ms}}. The shortest-lived isotope of lithium is {{SimpleNuclide|Lithium|4}} which decays through [[proton emission]] and has a half-life of {{val|7.58043|e=-23|u=s}}.

{{SimpleNuclide|Lithium|7}} is one of the [[primordial elements]] or, more properly, primordial isotopes, produced in [[Big Bang nucleosynthesis]] (a small amount of {{SimpleNuclide|Lithium|6}} is also produced in stars). Lithium isotopes fractionate substantially during a wide variety of natural processes, including [[mineral formation]] (chemical precipitation), [[metabolism]], and [[ion exchange]]. Lithium ion substitutes for [[magnesium]] and [[iron]] in octahedral sites in [[clay]] minerals, where {{SimpleNuclide|Lithium|6}} is preferred to {{SimpleNuclide|Lithium|7}}, resulting in enrichment of the light isotope in processes of hyperfiltration and rock alteration.

==Isotopes==
===Lithium-4===
'''Lithium-4''' contains 3 [[proton]]s and one [[neutron]]. It is the shortest lived isotope of lithium. It decays by [[proton emission]] and has a half-life of {{val|9.1|e=-23|u=s}}.<!--previous: {{val|7.58043|e=-23}}--> It can be formed as an intermediate in some nuclear fusion reactions.

===Lithium-6===
'''Lithium-6''' is valued as a source material for [[tritium]] production and as a neutron absorber in [[nuclear fusion]]. Large amounts of lithium-6 have been isotopically fractionated for use in [[nuclear weapon]]s.

===Lithium-7===
Some of the material remaining from the production of lithium-6, which is depleted in lithium-6 and enriched in '''lithium-7''', is made commercially available, and some has been released into the environment. Relative lithium-7 abundances as high as 35.4% greater than the natural value have been measured in ground water from a carbonate aquifer underlying West Valley Creek, Pennsylvania (USA), down-gradient from a lithium processing plant. In depleted material, the relative {{SimpleNuclide|Lithium|6}} abundance may be reduced by as much as 80% of its normal value, giving the [[atomic mass]] a range from {{val|6.94|u=u}} to more than {{val|6.99|u=u}}. As a result, the isotopic composition of lithium is highly variable depending on its source. An accurate [[relative atomic mass]] cannot be given representatively for all samples.

== Table ==
{| class="wikitable" style="font-size:95%; white-space:nowrap"
! rowspan="2" | nuclide<br />symbol
! Z({{SubatomicParticle|link=yes|Proton}})
! N({{SubatomicParticle|link=yes|Neutron}})
! &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
|-
| {{SimpleNuclide|Lithium|4}}
| style="text-align:right" | 3
| style="text-align:right" | 1
| {{val|4.02719|(23)}}
| {{val|91|(9)|e=-24|u=s}} [{{val|6.03|u=MeV}}]
| 2-
|
|
|-
| {{SimpleNuclide|Lithium|5}}
| style="text-align:right" | 3
| style="text-align:right" | 2
| {{val|5.01254|(5)}}
| {{val|370|(30)|e=-24|u=s}} [~{{val|1.5|u=MeV}}]
| 3/2-
|
|
|-
| {{SimpleNuclide|Lithium|6}}
| style="text-align:right" | 3
| style="text-align:right" | 3
| {{val|6.015122795|(16)}}
| STABLE
| 1+
| [{{val|0.0759|(4)}}]
| {{val|0.07714}}-{{val|0.07225}}
|-
| {{SimpleNuclide|Lithium|7}}
| style="text-align:right" | 3
| style="text-align:right" | 4
| {{val|7.01600455|(8)}}
| STABLE
| 3/2-
| [{{val|0.9241|(4)}}]
| {{val|0.92275}}-{{val|0.92786}}
|-
| {{SimpleNuclide|Lithium|8}}
| style="text-align:right" | 3
| style="text-align:right" | 5
| {{val|8.02248736|(10)}}
| {{val|840.3|(9)|u=ms}}
| 2+
|
|
|-
| {{SimpleNuclide|Lithium|9}}
| style="text-align:right" | 3
| style="text-align:right" | 6
| {{val|9.0267895|(21)}}
| {{val|178.3|(4)|u=ms}}
| 3/2-
|
|
|-
| {{SimpleNuclide|Lithium|10}}
| style="text-align:right" | 3
| style="text-align:right" | 7
| {{val|10.035481|(16)}}
| {{val|2.0|(5)|e=-21|u=s}} [{{val|1.2|(3)|u=MeV}}]
| (1-,2-)
|
|
|-
| style="text-indent:1em" | {{SimpleNuclide|Lithium|10|m1}}
| colspan="3" style="text-indent:2em" | {{val|200|(40)|u=keV}}
| {{val|3.7|(15)|e=-21|u=s}}
| 1+
|
|
|-
| style="text-indent:1em" | {{SimpleNuclide|Lithium|10|m2}}
| colspan="3" style="text-indent:2em" | {{val|480|(40)|u=keV}}
| {{val|1.35|(24)|e=-21|u=s}}
| 2+
|
|
|-
| {{SimpleNuclide|Lithium|11}}
| style="text-align:right" | 3
| style="text-align:right" | 8
| {{val|11.043798|(21)}}
| {{val|8.75|(14)|u=ms}}
| 3/2-
|
|
|-
| {{SimpleNuclide|Lithium|12}}
| style="text-align:right" | 3
| style="text-align:right" | 9
| {{val|12.05378|(107)}}#
| <{{val|10|u=ns}}
|
|
|
|}

=== Notes ===
* The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
* 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.
* In depleted material, the relative {{SimpleNuclide|Lithium|6}} abundance may be reduced by as much as 80% of its normal value, giving the atomic mass a range from {{val|6.94|u=u}} to more than {{val|6.99|u=u}}.
* 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.
* {{SimpleNuclide|Lithium|11}} has a [[Nuclear halo]] of two weakly linked neutrons, thus explaining an important difference in the radius.

== 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.

{{Isotope nav | element=lithium | lighter=Isotopes of helium | heavier=Isotopes of beryllium }}

[[Category:Isotopes|Lithium]]
[[Category:Lithium]]

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