Radioactive carbon dating rocks
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.The mass defect of an atom reflects the stability of the nucleus.It is equal to the energy released when the nucleus is formed from its protons and neutrons.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.The solid line represents a neutron to proton ratio of 1:1.
The energy given off in this reaction is carried by an x-ray photon, which is represented by the symbol hv, where h is Planck's constant and v is the frequency of the x-ray.The synthesis of a mole of helium releases 3.4 million times as much energy.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.
The reaction is usually accompanied by the ejection of one or more neutrons.