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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.
This list of nuclides shows observed nuclides that either are stable or, if radioactive, have half-lives longer than one hour. This represents isotopes of the first 105 elements, except for elements 87 ( francium ), 102 ( nobelium ) and 104 ( rutherfordium ).
This is a list of chemical elements by the stability of their isotopes. Of the first 82 elements in the periodic table , 80 have isotopes considered to be stable. [ 1 ] Overall, there are 251 known stable isotopes in total.
Radioactive isotopes are used in medicine for both treatment and diagnostic scans. The most common isotope used in diagnostic scans is Technetium-99m, used in approximately 85% of all nuclear medicine diagnostic scans worldwide.
A chart or table of nuclides maps the nuclear, or radioactive, behavior of nuclides, as it distinguishes the isotopes of an element.It contrasts with a periodic table, which only maps their chemical behavior, since isotopes (nuclides that are variants of the same element) do not differ chemically to any significant degree, with the exception of hydrogen.
Natural radioisotopes [ edit ] Many years ago radium-226 and radon-222 were used as gamma-ray sources for industrial radiography : for instance, a radon-222 source was used to examine the mechanisms inside an unexploded V-1 flying bomb , while some of the early Bathyspheres could be examined using radium-226 to check for cracks.
In nuclear medicine, radioisotopes are used for diagnosis, treatment, and research. Radioactive chemical tracers emitting gamma rays or positrons can provide diagnostic information about internal anatomy and the functioning of specific organs, including the human brain.
Natural isotopes are either stable isotopes or radioactive isotopes that have a sufficiently long half-life to allow them to exist in substantial concentrations in the Earth (such as bismuth-209, with a half-life of 1.9 × 10 19 years, potassium-40 with a half-life of 1.251(3) × 10 9 years), daughter products of those isotopes (such as 234 Th, with a half-life of 24 days) or cosmogenic ...