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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]
Bismuth-209 was long thought to have the heaviest stable nucleus of any element, but in 2003, a research team at the Institut d’Astrophysique Spatiale in Orsay, France, discovered that 209 Bi undergoes alpha decay with a half-life of 20.1 exayears (2.01×10 19, or 20.1 quintillion years), [3] [4] over 10 9 times longer than the estimated age of the universe. [5]
With the longest-lived isotope of technetium, 97 Tc, having a 4.21-million-year half-life, [10] no technetium remains from the formation of the Earth. [ 11 ] [ 12 ] Only minute traces of technetium occur naturally in Earth's crust—as a product of spontaneous fission of 238 U, or from neutron capture in molybdenum —but technetium is present ...
The age of Earth is about 4.54 billion years; [7] [33] [34] the earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago according to the stromatolite record. [35] Some computer models suggest life began as early as 4.5 billion years ago. [36] [37] The oldest evidence of life is indirect in the form of isotopic ...
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 ...
A life form (also spelled life-form or lifeform) is an entity that is living, [1] [2] such as plants , animals , and fungi . It is estimated that more than 99% of all species that ever existed on Earth, amounting to over five billion species, [3] are extinct. [4] [5] Earth is the only celestial body known to harbor life forms. No form of ...
C within its biological material at that time will continue to decay, and so the ratio of 14 C to 12 C in its remains will gradually decrease. Because 14 C decays at a known rate, the proportion of radiocarbon can be used to determine how long it has been since a given sample stopped exchanging carbon – the older the sample, the less 14 C ...
A star, HH 46-IR, resembling the sun early in its life, is surrounded by a disk of material which contains molecules including cyanide compounds, hydrocarbons, and carbon monoxide. PAHs in the interstellar medium can be transformed through hydrogenation , oxygenation , and hydroxylation to more complex organic compounds used in living cells.