Search results
Results from the WOW.Com Content Network
A similar radiogenic series is derived from the long-lived radioactive primordial nuclide 232 Th. These nuclides are described as geogenic, meaning that they are decay or fission products of uranium or other actinides in subsurface rocks. [6] All such nuclides have shorter half-lives than their parent radioactive primordial nuclides.
The Solar System and Earth are formed from primordial nuclides and extinct nuclides. Extinct nuclides have decayed away, but primordial nuclides still exist in their original state (undecayed). There are 251 stable primordial nuclides, and remainders of 35 primordial radionuclides that have very long half-lives.
(t 1/2 = 4.5 × 10 9 years) of uranium is still fairly abundant in nature, but the shorter-lived isotope 235 U (t 1/2 = 0.7 × 10 9 years) is 138 times rarer. About 34 of these nuclides have been discovered (see List of nuclides and Primordial nuclide for details). The second group of radionuclides that exist naturally consists of radiogenic ...
One of the primordial nuclides is tantalum-180m, which is predicted to have a half-life in excess of 10 15 years, but has never been observed to decay. The even-longer half-life of 2.2 × 10 24 years of tellurium-128 was measured by a unique method of detecting its radiogenic daughter xenon-128 and is the longest known experimentally measured ...
They include 30 nuclides with measured half-lives longer than the estimated age of the universe (13.8 billion years [17]), and another four nuclides with half-lives long enough (> 100 million years) that they are radioactive primordial nuclides, and may be detected on Earth, having survived from their presence in interstellar dust since before ...
Learn how to download and install or uninstall the Desktop Gold software and if your computer meets the system requirements.
However, nucleogenic isotopes should not be confused with much more common radiogenic nuclides that are also younger than primordial nuclides, but which arise as simple daughter isotopes from radioactive decay. Nucleogenic isotopes, as noted, are the result of a more complicated nuclear reaction, although such reactions may begin with a ...
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!