Nuclear binding energy
The minimum
energy required to break a nucleus down into its individual nucleons (i.e.
protons and neutrons) is called nuclear binding energy of the nucleus.
Binding
energy in a nucleus is the result of the interplay between two forces: the
attractive strong nuclear force (one of the fundamental forces) that
binds the nucleons and the repulsive electromagnetic force between
the positively charged protons.
The binding
energy per nucleon is the binding energy of the nucleus divided by the
number of nucleons in the nucleus. It indicates how strongly each nucleon is
bound to the rest of the nucleus. Nuclei with higher binding energies per
nucleon are more stable.
Mass defect
When
nucleons are not bound into an atom, they are in a higher energy
state than when they are part of an atom. Part of the mass-energy
possessed by the nucleons when they are isolated is used to bind them together
in a nucleus.
The mass
defect is the difference between the total mass of the individual nucleons
(when they are not bound together in a nucleus) and the mass of the nucleus as
a whole.
The relationship
between binding energy and mass defect builds is given by Einstein's
mass-energy equivalence:
EBE=mdc2
Where
EBE is Binding Energy, md is mass defect c is the
velocity of light.
Nuclear stability
 |
| Binding Energy per Nucleon Vs Mass No Curve |
Atoms lighter
than iron (i.e. with atomic mass), the binding energy per nucleon generally increases with
increasing nucleon number.
Atoms
heavier than iron the binding energy per
nucleon decreases with increasing nucleon number of the nucleus.
