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Posted by / 20-Aug-2018 18:41

Problems with k ar dating

A more useful quantity is obtained by dividing the binding energy for a nuclide by the total number of protons and neutrons it contains.This quantity is known as the binding energy per nucleon.Binding energies are usually expressed in units of electron volts (e V) or million electron volts (Me V) per atom.Binding energies gradually increase with atomic number, although they tend to level off near the end of the periodic table.Although it is not obvious at first, -decay increases the ratio of neutrons to protons.Consider what happens during the -decay of The difference between the mass of an atom and the sum of the masses of its protons, neutrons, and electrons is called the mass defect.A graph of the number of neutrons versus the number of protons for all stable naturally occurring nuclei.

Since most nuclear reactions are carried out on very small samples of material, the mole is not a reasonable basis of measurement.The binding energy per nucleon ranges from about 7.5 to 8.8 Me V for most nuclei, as shown in the figure below.It reaches a maximum, however, at an atomic mass of about 60 amu.It can capture an electron or it can emit a positron.Electron emission therefore leads to an increase in the atomic number of the nucleus.

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The excess energy associated with this excited state is released when the nucleus emits a photon in the -ray portion of the electromagnetic spectrum.