Isotopes of lithium

# Overview
Naturally occurring lithium (Li) (standard atomic mass: 6.941(2) u) is composed of two stable isotopes (Template:SimpleNuclide and Template:SimpleNuclide, the latter being the more abundant (92.5% natural abundance). Seven radioisotopes have been characterized, the most stable being Template:SimpleNuclide with a half-life of 6999838000000000000838 ms and Template:SimpleNuclide with a half-life of 6999178300000000000178.3 ms. All of the remaining radioactive isotopes have half-lives that are shorter than 69978600000000000008.6 ms. The shortest-lived isotope of lithium is Template:SimpleNuclide which decays through proton emission and has a half-life of 69777580429999999997.580431023 s.

# Isotopes

## Lithium-4
Lithium-4 contains 3 protons and one neutron. It is the shortest lived isotope of lithium. It decays by proton emission and has a half-life of 69779099999999999999.11023 s. 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 weapons.

## 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 Template:SimpleNuclide abundance may be reduced by as much as 80% of its normal value, giving the atomic mass a range from 70006940000000000006.94 u to more than 70006990000000000006.99 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

## 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 Template:SimpleNuclide abundance may be reduced by as much as 80% of its normal value, giving the atomic mass a range from 70006940000000000006.94 u to more than 70006990000000000006.99 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.
- Template:SimpleNuclide has a Nuclear halo of two weakly linked neutrons, thus explaining an important difference in the radius.