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Mg to 40 Mg (with the exception of 39 Mg). The longest-lived radioisotope is 28 Mg with a half-life of 20.915(9) h. The lighter isotopes mostly decay to isotopes of sodium while the heavier isotopes decay to isotopes of aluminium. The shortest-lived is proton-unbound 18 Mg with a half-life of 4.0(3.4) zeptoseconds.
Magnesium has three stable isotopes: 24 Mg, 25 Mg and 26 Mg. All are present in significant amounts in nature (see table of isotopes above). About 79% of Mg is 24 Mg. The isotope 28 Mg is radioactive and in the 1950s to 1970s was produced by several nuclear power plants for use in scientific experiments. This isotope has a relatively short half ...
A table or chart of nuclides is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons (symbol N) and the other represents the number of protons (atomic number, symbol Z) in the atomic nucleus. Each point plotted on the graph thus represents a nuclide of a known or hypothetical chemical element.
Of the 26 "monoisotopic" elements that have only a single stable isotope, all but one have an odd atomic number—the single exception being beryllium. In addition, no odd-numbered element has more than two stable isotopes, while every even-numbered element with stable isotopes, except for helium, beryllium, and carbon, has at least three.
The unit of activity is the becquerel (symbol Bq), which is defined equivalent to reciprocal seconds (symbol s −1). The older, non-SI unit of activity is the curie (Ci), which is 3.7 × 10 10 radioactive decays per second. Another unit of activity is the rutherford, which is defined as 1 × 10 6 radioactive decays per second.
Radioactive nonprimordial, but naturally occurring on Earth. 61 347 Carbon-14 (and other isotopes generated by cosmic rays) and daughters of radioactive primordial elements, such as radium, polonium, etc. 41 of these have a half life of greater than one hour. Radioactive synthetic half-life ≥ 1.0 hour). Includes most useful radiotracers. 662 989
Aluminium-26 (26 Al, Al-26) is a radioactive isotope of the chemical element aluminium, decaying by either positron emission or electron capture to stable magnesium-26.The half-life of 26 Al is 717,000 years.
Isotopes of an element are distinguished by mass number (total protons and neutrons), with this number combined with the element's symbol. IUPAC prefers that isotope symbols be written in superscript notation when practical, for example 12 C and 235 U. However, other notations, such as carbon-12 and uranium-235, or C-12 and U-235, are also used.