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The high number of isotopes is consistent with lead's atomic number being even. [g] Lead has a magic number of protons (82), for which the nuclear shell model accurately predicts an especially stable nucleus. [39] Lead-208 has 126 neutrons, another magic number, which may explain why lead-208 is extraordinarily stable. [39]
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
For instance, the magic number 8 occurs when the 1s 1/2, 1p 3/2, 1p 1/2 energy levels are filled, as there is a large energy gap between the 1p 1/2 and the next highest 1d 5/2 energy levels. The atomic analog to nuclear magic numbers are those numbers of electrons leading to discontinuities in the ionization energy.
The darker more stable isotope region departs from the line of protons (Z) = neutrons (N), as the element number Z becomes larger. 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 ...
The atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons , this is equal to the proton number ( n p ) or the number of protons found in the nucleus of every atom of that element.
Certain elements have no stable isotopes and are composed only of radioisotopes: specifically the elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with atomic number greater than 82. Of the 80 elements with at least one stable isotope, 26 have only one stable isotope.
The stability of nuclei decreases greatly with the increase in atomic number after curium, element 96, so that all isotopes with an atomic number above 101 decay radioactively with a half-life under a day. No elements with atomic numbers above 82 (after lead) have stable isotopes. [107]
There are 6 stable nuclides and one radioactive primordial nuclide with neutron number 82 (82 is the neutron number with the most stable nuclides, since it is a magic number): barium-138, lanthanum-139, cerium-140, praseodymium-141, neodymium-142, and samarium-144, as well as the radioactive primordial nuclide xenon-136, which decays by a very ...