A short note on examples of isotones

All matter is made up of atoms in different arrangements. Atoms are made up of protons, neutrons and electrons. Every proton has a positive charge and every electron has a negative charge. Neutrons have no charge; that is, it is neutral. It is a vital concept in nuclear physics. It is an indispensable part of both physics and chemistry. The meaning of isotones is much more clearly explained with the help of several examples in this article.

Definition of isotones

Isotones can be defined as two or more nuclei of atoms consisting of the same number of neutrons. In simple words, atoms with the same number of neutrons but different protons are termed isotones. Therefore, we see two conditions for an atom or nuclei to be an isotone. 

1. The atom or nuclei should have the same number of neutrons. 
2. They should have different numbers of protons. 

Atoms in isotones may have different atomic numbers and different atomic masses.

Elements of isotones

Neutrons

Neutrons were discovered in May 1932 by the English physicist James Chadwick, who asserted that neutrons were a new fundamental particle devoid of any charge. These particles lacked both positive and negative charges and were neutral in charge, so he named them neutrons. In simple words, they are without charge. From the conservation of momentum and energy, he derived the mass of neutrons. He also noticed that the mass of a neutron is very close to the mass of a proton. 

MN = 1.00866

U = 1.6749 × 10-27 kg

The discovery of neutrons led to a better understanding of atomic number (the number of protons and electrons) and atomic mass (the total number of neutrons and protons). The number of neutrons in an atom or nuclei is represented by N.

Protons

Protons were discovered in 1886 by Eugen Goldstein. ‘Proton’ means first in Greek. Ernest Rutherford gave this name in 1920 to the hydrogen nucleus. Proton is a subatomic particle having a positive charge. The positive charge of a proton is equal in magnitude to a unit of electron charge. The mass of a proton is equal to 1.67262 × 10-27 kg. One or more protons are present in the nucleus of every atom or nuclei. They form a crucial part of the nucleus and are represented by the symbol p or p+. They play an important role in the identification of atomic numbers. 

Examples of isotones

Isotones are atoms having a similar number of neutrons and different protons. There are several examples of isotones. Some of the examples of isotones include: 

• Carbon-12, nitrogen-13 and oxygen-14. The three of them have six neutrons, and the number of protons in carbon is six, in nitrogen is seven and in oxygen is eight.
• Boron-12 and carbon-13 are isotones as both have seven neutrons.
• Sulphur-36, Chlorine-37, Argon-38, Potassium-39 and Calcium-40 are all isotones of twenty because they have twenty neutrons.
• Hydrogen-2 and Helium-3 are isotones of neutron one.
• Beryllium-9 and Boron-10 are isotones of neutron five.
• Carbon-13 and Nitrogen-14 are isotones of seven.
• Krypton-86, Yttrium-89, Zirconium-90, Molybdenum-92 and Radium-88 are isotones of neutron fifty. 

Uses of isotones

When scientists study numerous nucleic varieties, it is helpful to look at nuclei with the same number of neutrons. However, altering the number of protons changes the chemical nature of the nucleus. Isotones are used for different purposes in nuclear power plants and to form nuclear bombs. Some of the applications of isotones are: 

1. Isotones can be found in various neutron applications. A typical example is the production of technetium-99 used in medical imaging, which is produced by neutron radiation of molybdenum-98 targets. Isotopes that lead to higher cross-sections produce more products and therefore are more efficient.
2. Another application is in the production of fissionable material for nuclear weapons. This can be done by exposing a heavy isotope, usually uranium-235 or plutonium-239, to fast neutrons via bombardment with deuterons accelerated in a particle accelerator or cyclotron. The resulting compound nucleus emits more neutrons on average than it absorbs, increasing the chance of successful fission.
3. In addition to its use in military applications, isotones can be used as neutron absorbers for reactor control. Generally, reactivity increases when the void (i.e., unfilled) fraction of a reactor’s core is reduced; however, too few neutrons will be absorbed to maintain a chain reaction. Isotones that cannot absorb a neutron or do so only with a long delay will thus reduce reactivity. 
4. Isotones also play a significant role in research reactors. Again, these are used to control power levels using absorbers that will not interfere with the neutron flux by absorbing neutrons or decaying into undesirable isotopes.

Conclusion

In this section, we have discussed several things about isotones as well as their definition, meaning and examples. We learned that they play an important role in nuclear physics. The number of neutrons and protons characterises them. According to the definition, if the number of protons in an atom is different and the number of neutrons is the same, it will be termed isotones. There are several applications and uses of isotones in the field of physics. Apart from this, it also plays a vital role in chemistry. They are used in hospitals for medical imaging and also in the production of nuclear weapons.