Binding Energy Curve

Binding Energy Curve :
A graph is plotted for different nuclei between the binding energy per nucleon and the atomic mass number. This graph gives a curve which is called " binding energy curve".
Average binding energy curve
There are following discussion point obtained from the binding energy curve :

1.) For Nuclei with $A=50$ TO $A=80$:

  • For nuclei with atomic mass number $A = 50 - 80$ , the B.E./ nucleon (i.e. binding energy per nucleon) is approximately $8.5 MeV$.

  • The curve is almost flat in this and indicate the highly stability of the nucleus.

    2.) For Nuclei with $A \geq 80$:


  • For heavier nuclei with $A \gt 80$, the B.E. /nucleon ( i.e. binding energy per nucleon) decreases slowly and reaching about $7.6 MeV$ for uranium ($U \: A = 238$).

  • The lower value of binding energy per nucleon fails to counteract the Coulombian repulsion among protons in nuclei having large number of protons resulting instability

  • Consequently, the nuclei of heavier atoms beyond $_{83}Bi^{209}$ are radioactive.


  • 3.) For Nuclei with $A \leq 50$:

  • For nuclei with atomic mass number below $50$ , the B.E./ nucleon decreases, with a sharp drop below $A=20$.

  • For example: Heavy hydrogen (i.e $_{1}H^{2}$), it is only about $1.1 MeV$. it indicates that lower stability for nuclear with mass number below $20$.


  • 4.) Subsidiary Peak for $A \lt 50$:

  • Below $A = 50$, the curve does not fall continuously, but the subsidiary peaks at $_{8}O^{16}, _{6}C^{12},_{2}He^{4}$.

  • These peak indicate that such even-even nuclear are more stable compared to the immediate neighbours .


  • 5.) Nuclear fusion and Nuclear fission process release energy:

    From curve, it shows that drops down in curve at both high and low mass number and lower binding energy per nucleon.

    For example:

    A very high amount of energy is released in the process of nuclear fission and fusion because of Lo binding energy causes instability of the nucleus.

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