Dating rocks and soils
The mass defect is therefore also known as the binding energy of the nucleus. It measures the difference between the stability of the products of the reaction and the starting materials.
The larger the binding energy, the more stable the nucleus.
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.
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.
Alpha decay of the The sum of the mass numbers of the products (234 4) is equal to the mass number of the parent nuclide (238), and the sum of the charges on the products (90 2) is equal to the charge on the parent nuclide.
Nuclei can also decay by capturing one of the electrons that surround the nucleus.