An extinct radionuclide is one which was thought to have been formed by a primordial process such as stellar nucleogenesis in the supernova(s) which contributed radioisotopes to the early solar system, about 4. A radionuclide is an Atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created In Physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than those of H-1 (i A supernova (plural supernovae or supernovas) is a stellar Explosion. 6 billion years ago. Generally, radioisotopes with a decay half-life shorter than about 100 million years are not found in nature, unless known to be generated continuously by a natural process, such as cosmic rays, or a decay chain of much longer lived isotopes, such as uranium or thorium. Half-Life (computer-game page here It's already listed in the disambiguation page For the 1962 Bruce Conner film see Cosmic Ray (film Cosmic rays are energetic particles originating from space that impinge on Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90 These short-lived isotopes are thus seen only as extinct radionuclides, presenting now as only a superabundance of their stable decay products.
Examples of extinct radionuclides include iodine-129 (the first to be noted in 1960, and inferred from excess xenon-129 concentrations in meteorites, in the xenon-iodine dating system) and aluminium-26 (also inferred from extra magnesium-26 found in meteorites). Iodine-129 (129I is a Radioisotope of Iodine. Formation and decay 129I is primarily formed from the Fission Naturally occurring Xenon ( Xe) is made of nine stable Isotopes (124Xe 134Xe and 136Xe are predicted to undergo Aluminium ( Al) has multiple Isotopes Only 27Al ( Stable isotope) and 26Al ( radioactive isotope ''t''1/2 Magnesium ( Mg)Standard atomic mass 243050(6 u Table
A partial list of radionuclides which are not found in nature, but for which decay products are found, is:
Some notable isotopes with shorter lives still being produced on Earth include:
Radioactives with half-lives shorter than one million years are also produced: for example, carbon-14 by cosmic ray production in the atmosphere (half life 5730 years). Carbon-14, 14C, or radiocarbon, is a Radioactive isotope of Carbon discovered on February 27, 1940, by