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Oxygen-related isotopologues of water include the commonly available form of heavy-oxygen water (H 2 18 O) and the more difficult to separate version with the 17 O isotope. Both elements may be replaced by isotopes, for example in the doubly labeled water isotopologue D 2 18 O.
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.
Radioactive isotopes ranging from 11 O to 28 O have also been characterized, all short-lived. The longest-lived radioisotope is 15 O with a half-life of 122.266(43) s, while the shortest-lived isotope is the unbound 11 O with a half-life of 198(12) yoctoseconds, though half-lives have not been measured for the unbound heavy isotopes 27 O and 28 ...
A nuclide is a species of an atom with a specific number of protons and neutrons in the nucleus, for example, carbon-13 with 6 protons and 7 neutrons. The nuclide concept (referring to individual nuclear species) emphasizes nuclear properties over chemical properties, whereas the isotope concept (grouping all atoms of each element) emphasizes chemical over nuclear.
Radiochemistry is the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads to a substance being described as being inactive as the isotopes are stable).
The radioactive decay can produce a stable nuclide or will sometimes produce a new unstable radionuclide which may undergo further decay. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay.
Naturally occurring cobalt, Co, consists of a single stable isotope, 59 Co (thus, cobalt is a mononuclidic element). Twenty-eight radioisotopes have been characterized; the most stable are 60 Co with a half-life of 5.2714 years, 57 Co (271.811 days), 56 Co (77.236 days), and 58 Co (70.844 days).
Nitrogen-14 is the source of naturally-occurring, radioactive, carbon-14. Some kinds of cosmic radiation cause a nuclear reaction with nitrogen-14 in the upper atmosphere of the Earth, creating carbon-14, which decays back to nitrogen-14 with a half-life of 5700(30) years .