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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.
The column labeled "energy" denotes the energy equivalent of the mass of a neutron minus the mass per nucleon of this nuclide (so all nuclides get a positive value) in MeV, formally: m n − m nuclide / A, where A = Z + N is the mass number. Note that this means that a higher "energy" value actually means that the nuclide has a lower energy.
The first printed edition of the Karlsruhe Nuclide Chart of 1958 in the form of a wall chart was created by Walter Seelmann-Eggebert and his assistant Gerda Pfennig. Walter Seelmann-Eggebert was director of the Radiochemistry Institute in the 1956 founded "Kernreaktor Bau- und Betriebsgesellschaft mbH" in Karlsruhe, Germany (a predecessor institution of the later "(Kern-)Forschungszentrum ...
Interactive Chart of Nuclides (Brookhaven National Laboratory) The Lund/LBNL Nuclear Data Search; An isotope table with clickable information on every isotope and its decay routes is available at chemlab.pc.maricopa.edu; An example of free Universal Nuclide Chart with decay information for over 3000 nuclides is available at Nucleonica.net.
The Mattauch isobar rule states that if two adjacent elements on the periodic table have isotopes of the same mass number, at least one of these isobars must be a radionuclide (radioactive). In cases of three isobars of sequential elements where the first and last are stable (this is often the case for even-even nuclides, see above ), branched ...
However, the next even nuclide outside the one-particle drip line may still be particle stable if its two-particle separation energy is non-negative. This is possible because the two-particle separation energy is always greater than the one-particle separation energy, and a transition to a less stable odd nuclide is energetically forbidden.
The shape of the valley is roughly an elongated paraboloid corresponding to the nuclide binding energies as a function of neutron and atomic numbers. [1] The nuclides within the valley of stability encompass the entire table of nuclides. The chart of those nuclides is also known as a Segrè chart, after the physicist Emilio Segrè. [3]
The first table is for even-atomic numbered elements, which tend to have far more primordial nuclides, due to the stability conferred by proton-proton pairing. A second separate table is given for odd-atomic numbered elements, which tend to have far fewer stable and long-lived (primordial) unstable nuclides. [citation needed]