Binding Energy per Nucleon

Binding energy per nucleon is the minimum energy required to disassemble the nucleus of an atom into its constituent neutrons and protons. The same amount of energy is also required to combine individual protons and neutrons into a single nucleus. The protons are positively charged, so there are forces of repulsion between them. To hold the nucleons together, the nucleus gains the binding energy per nucleon. 

For example, the mass number of iron is 56, and it is considered one of the most stable elements, which means iron has relatively high binding energy per nucleon. 

For stable nuclei, the binding energy per nucleon is always a positive number because the nucleus requires some amount of energy for the nucleons to separate. When the nucleons are far apart, the binding energy per nucleon is considered a negative number. 

Here is an example to explain the binding energy per nucleon. As we know, hydrogen has two nuclei composed of a neutron and proton. Say it can be separated by providing 2.23 million electron volts (MeV) of energy. The same amount of energy, i.e, 2.23 MeV is liberated in the form of gamma radiation and will be required to form two nucleus hydrogen, combining a slowly moving proton and neutron. The sum of the masses of the discrete particles is more than the total mass of the particles.

Ionisation Potential

A certain amount of energy is required to remove an electron from an atom. This energy is called ionisation potential. Ionisation potential can also remove a molecule or an ion. Generally, the binding energy per nucleon is much greater than the binding energy of a single electron.

Binding Energy Per Nucleon Curve

The curve for binding energy per nucleon is obtained by dividing the maximum nuclear binding energy by the number of nucleons. The range of binding energies of nucleons is millions of MeV, compared to tens of electron volts for atomic electrons. In the range of a few electron volts, an atomic transition might emit a photon in the visible light region. In the MeV range, nuclear transitions can emit quantum energies with gamma-rays.

Iron limit

In the nuclear fusion processes in stars, the buildup of heavier elements is limited to elements below the iron. It is so because the fusion of iron will subtract some amount of energy rather than provide it. The atomic number of iron is 56, and it is abundant in stellar processes. Iron has 8.8 MeV binding energy per nucleon and is known as the third most tightly bound of the nuclides. The average binding energy per nucleon of iron is exceeded by 58Fe and 62Ni. Nickel is considered the topmost tightly bound of the nuclides.

Foundation of Nuclear Energy

All the energy ever produced comes from basic physical processes or chemical processes. It has been accomplished by utilising power from wind, sun, and water or burning carbon-based materials like gas, coal, or wood. 

Fission and fusion

The two physical processes that produce huge amounts of energy from atoms are fission and fusion. Through nuclear reactions, the process of fission and fusion yields a million times more energy.

Fission

The term fission was coined by scientists Otto Frisch and Lise Meitner. They coined this name after the term “binary fission”, a term used in biology to describe cell division. Fission takes place the same way cells divide. The process of fission occurs when atoms split into smaller particles. It takes place when a large isotope is bombarded by high-speed particles, say neutrons. These neutrons are bombarded into the unstable isotope, which causes fission or breaking it into smaller pieces. During this process, a neutron strikes the desired nucleus in nuclear power reactors that majorly use uranium-235. The nuclear power reactor splits the targeted nucleus into two smaller isotopes called fission products, releasing a large amount of energy and three high-speed neutrons. The energy released, as a result, is then used in nuclear reactors to heat water and produce electricity. The high-speed neutrons become projectiles and initiate other fission reactions, also known as chain reactions.

Fusion

When two atoms collide, they form a heavier atom, just like helium is formed when two hydrogen atoms slam together. It is the same process throughout. A good example of this would be the sun, which creates huge amounts of energy. A high amount of pressure and temperature are required to join the nuclei together, due to which it is difficult to sustain for long periods. Fusion reactions are still being studied by scientists.

In fission, an unstable nucleus turns into stable nuclei with less total mass. This mass defect or the difference in mass is the binding energy that is released. The mass of the nucleus created in fusion is a little less than the mass of the main nuclei. The mass defect is due to the released binding energy since the formed nucleus is more stable.

Conclusion

In this article binding energy per nucleon is discussed. Binding energy per nucleon is the minimum energy required to disassemble the nucleus of an atom into its constituent neutrons and protons. The same amount of energy is also required to combine individual protons and neutrons into a single nucleus. The curve for binding energy per nucleon is obtained by dividing the maximum nuclear binding energy by the number of nucleons.