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The most stable radioactive isotopes are technetium-97 with a half-life of 4.21 ± 0.16 million years and technetium-98 with 4.2 ± 0.3 million years; current measurements of their half-lives give overlapping confidence intervals corresponding to one standard deviation and therefore do not allow a definite assignment of technetium's most stable ...
Technetium (43 Tc) is one of the two elements with Z < 83 that have no stable isotopes; the other such element is promethium. [2] It is primarily artificial, with only trace quantities existing in nature produced by spontaneous fission (there are an estimated 2.5 × 10 −13 grams of 99 Tc per gram of pitchblende) [3] or neutron capture by molybdenum.
Iron-60 has a half-life of 2.6 million years, [12] [13] but was thought until 2009 to have a half-life of 1.5 million years. It undergoes beta decay to cobalt-60 , which then decays with a half-life of about 5 years to stable nickel-60.
The first, technetium, was created in 1937. [3] Plutonium (Pu, atomic number 94), first synthesized in 1940, is another such element. It is the element with the largest number of protons (atomic number) to occur in nature, but it does so in such tiny quantities that it is far more practical to synthesize it.
This was a form of radioactive decay which had never been observed before this time. Segrè and I were able to show that this radioactive isotope of the element with the atomic number 43 decayed with a half-life of 6.6 h [later updated to 6.0 h] and that it was the daughter of a 67-h [later updated to 66 h] molybdenum parent radioactivity.
For example, Technetium-99m is a radioactive tracer that medical imaging equipment tracks in the human body. [ 90 ] [ 111 ] [ 112 ] It is well suited to the role because it emits readily detectable 140 keV gamma rays , and its half-life is 6.01 hours (meaning that about 94% of it decays to technetium-99 in 24 hours). [ 113 ]
Technetium-99 (99 Tc) is an isotope of technetium that decays with a half-life of 211,000 years to stable ruthenium-99, emitting beta particles, but no gamma rays. It is the most significant long-lived fission product of uranium fission, producing the largest fraction of the total long-lived radiation emissions of nuclear waste .
[[Technetium (99m Tc) sestamibi]] ("Cardiolite") is widely used for imaging of the heart. Technetium forms a variety of coordination complexes with organic ligands. Many have been well-investigated because of their relevance to nuclear medicine. [19] Technetium forms a variety of compounds with Tc–C bonds, i.e. organotechnetium complexes.