Nuclear Chemistry

Nuclear chemistry is a branch of chemical science that involves studying the atom’s nucleus, forces in play within the nucleus and its reactions when subjected to various processes. It also deals with the radioactive nature of some elements and the energy released by bombarding nuclei of atoms with another nucleus. This branch of chemistry is also called radiochemistry as it deals with the reactions between atoms and nuclei of radioactive elements. Nuclear chemistry has numerous applications in many diverse fields, especially medicine.

Rutherford identified three types of rays based on their reaction to the plates and named them.

1. Alpha rays carry a positive charge and show affinity towards the negatively charged plate.
2. Beta rays carry a negative charge and deviate towards the positive plate.
3. Gamma rays are those that show no deviation or reaction.

Nuclear energy

Unlike the ordinary chemical reactions, the reactions in nuclear chemistry result in the release of not just the formation of particles but rather the transformation of elements and colossal amounts of energy called nuclear energy. Along with this, radiation is emitted as alpha, beta or gamma radiation.

Types of nuclear reactions

Instead of letting the nuclei decay naturally, humans have developed two methods that allow us to artificially divide or combine the nucleus to release enormous amounts of energy that can be utilised with proper infrastructure and technology. The two methods are:

• Nuclear fission: In this reaction, the nuclei of a heavier atom are bombed with a fast-moving neutron to break it up into a lighter nucleus of somewhat similar masses. This process releases energy that can be processed and converted into an alternative form of energy.
• Nuclear fusion: Here, two lighter nuclei are fused to create heavier nuclei while releasing even greater energy.

Nuclear forces

Primary forces in creation act inside the nucleus to bind the nucleons by rapidly exchanging nuclear particles known as mesons between protons and neutrons. The particles exchanged may be positive, negative or neutral. These forces act within extremely short ranges called fermi, where one fermi is equal to 10-15 cm. These forces are far stronger than electrostatic forces.    

Factors that affect the stability of the nucleus

• n/p ratio

It is one of the vital points that affect the stability of an atom. When an atom has the correct n/p ratio, it remains stable, but if it is higher than the specified ratio, the nucleus emits β–emissions to correct its n/p value. By this process, a neutron is converted into a proton to give out β and antineutrino, thus, increasing the number of protons and correcting the n/p value. Similarly, atoms with a low n/p value emit positrons to fix their n/p value. This phenomenon happens due to the atom’s tendency to attain stability.

• Binding energy

Binding energy refers to the energy generated when the nucleus is created or put together from its constituents. It means that nuclei with higher binding energy have more stability than atoms with low binding energy. Iron, with the highest binding energy, is the most stable nucleus. 

• Packing fraction

The packing fraction is a measure of the relative mass defects. The value of the packing fraction may be positive, zero or even negative. It is calculated by the formula: isotopic mass – A /A*104. Nuclei with positive packing fractions are unstable, while those with lower values tend to be relatively more stable.

Radioactivity 

The nuclei of an element from the F-block elements of the periodic table emit radiation without any outside interference. Such elements are known as radioactive elements. The degradation of the element on its own is called radioactivity. 

Radioactivity is the natural degradation or decay of an element without physical factors like temperature, pressure, etc. 

• Radioactive disintegration

Radioactive disintegration refers to the phenomenon of a single radioactive nucleus being transformed into another by the emission of radiation as needed. The radiation may be α, β, γ. Here γ-radiation is an aftereffect of radioactive disintegration, i.e., this type of radiation is emitted only after the release of α and β-radiations. Rutherford and Soddy proposed this theory in 1903. 

• Rate of disintegration 

Any element’s disintegration rate relies on the number of atoms of the radioactive element sample that disintegrate in a unit of time. The rate of decay can be expressed as rate of decay= -dN/dt proportional to N or -dN/dt =kN where k= decay constant. The total lifespan of a radioactive element is many decades.

• Half-life

It is the time taken by one-half of an isotope sample to decay completely. Thl= 0.693/k.

The activity of radioactive substances:

Activity refers to the number of disintegrations in a radioactive element per second; the elements with a high level of radiation decay faster than elements with low radiation.

Activity = k* wt of element*N(a)/ atomic weight of elements, where NA = avogadro number.

Uses of radioactive elements

• They are used to determine the exact age of things using the carbon dating technique, for instance, the age of fossils, wood or other ancient materials whose age could not be found using other methods.

The age of the fossils is calculated using t= 2303/k *log10 * N(0)/N ;

• Medical purposes: radioactive materials are used in CT scans and x-rays for diagnostic purposes.
• Radiation therapy is used to treat cancer patients. Sometimes it is also used for sterilising medical equipment.
• Electricity: we produce electricity through artificial atomic nuclear fission.

Conclusion

Nuclear chemistry is the branch of chemistry concerned with all radioactive processes and is based on radioactivity, the process of decaying radioactive materials. These materials are beneficial, but they are challenging to handle, and many safety conditions must be met. Nuclear chemistry deals with information and research about the atomic nucleus and its characteristics and properties when put through various processes. The atom releases colossal amounts of energy when undergoing fusion or fission.