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This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds. [1]
In this situation it is generally uncommon to talk about half-life in the first place, but sometimes people will describe the decay in terms of its "first half-life", "second half-life", etc., where the first half-life is defined as the time required for decay from the initial value to 50%, the second half-life is from 50% to 25%, and so on.
Radon-222 is generated in the uranium series from the alpha decay of radium-226, which has a half-life of 1600 years. Radon-222 itself alpha decays to polonium-218 with a half-life of approximately 3.82 days, making it the most stable isotope of radon. [1] Its final decay product is stable lead-206.
Mercury (as methylmercury) in the body has a half-life of about 65 days. Lead in the blood has a half life of 28–36 days. [29] [30] Lead in bone has a biological half-life of about ten years. Cadmium in bone has a biological half-life of about 30 years. Plutonium in bone has a biological half-life of about 100 years.
The high short-term radioactivity of spent nuclear fuel is primarily from fission products with short half-life.The radioactivity in the fission product mixture is mostly due to short-lived isotopes such as 131 I and 140 Ba, after about four months 141 Ce, 95 Zr/ 95 Nb and 89 Sr constitute the largest contributors, while after about two or three years the largest share is taken by 144 Ce/ 144 ...
There are 39 known isotopes and 17 nuclear isomers of tellurium (52 Te), with atomic masses that range from 104 to 142. These are listed in the table below. Naturally-occurring tellurium on Earth consists of eight isotopes. Two of these have been found to be radioactive: 128 Te and 130 Te undergo double beta decay with half-lives of, respectively, 2.2×10 24 (2.2 septillion) years (the longest ...
with a half-life of 30.1671 years and 134 Cs with a half-life of 2.0652 years. [6] All other isotopes have half-lives less than 2 weeks, most under an hour. Beginning in 1945 with the commencement of nuclear testing , caesium radioisotopes were released into the atmosphere where caesium is absorbed readily into solution and is returned to the ...
Due to the long half-life of 40 K, the technique is most applicable for dating minerals and rocks over 100,000 years old. For shorter timescales, it is unlikely that enough 40 Ar will have had time to accumulate to be accurately measurable. K–Ar dating was instrumental in developing the geomagnetic polarity time scale. [2]