Nuclear Chemistry

NUCLEAR CHEMISTRY

Nuclear chemistry is a branch of chemistry that deals with the study of nuclear reactions and their applications. It involves the study of atomic nuclei, their properties, and the changes they undergo. Nuclear reactions involve changes in the structure of atomic nuclei, and as a result, they often release large amounts of energy.

Nuclear chemistry plays a crucial role in various fields such as nuclear power generation, nuclear medicine, and radiation therapy for cancer treatment. In nuclear power generation, nuclear reactions are used to generate electricity by heating water to produce steam, which is then used to drive turbines. In nuclear medicine, radioactive isotopes are used to diagnose and treat diseases such as cancer.

The study of nuclear chemistry involves understanding the behavior of atomic nuclei, the interactions between subatomic particles, and the different types of radiation emitted during nuclear reactions. Nuclear chemistry also involves the study of nuclear decay, nuclear fission, and nuclear fusion. The application of nuclear chemistry ranges from the production of nuclear energy to the treatment of cancer and the study of the origin and evolution of the universe.

 

Radiations

Radiation refers to the emission of energy in the form of particles or waves from the nucleus of an atom. These radiations can be classified into three types: alpha (α), beta (β), and gamma (γ) radiation. 

Radioactive element:-

  • Elements that exhibit the phenomenon of radioactivity are called radioactive elements.
  • The radioactive substance must kept in the container of Lead.

Types of radioactive elements :

  • Natural radioactive element- Po, At, Rn, Fr, Ra, Ac, Th, Pa, U
  • Artificial radioactive element-Np, Pu, to Habnium(Hb)
  • The idea of artificial radioactivity first came to the mind of F.Joliot in 1934.

Characteristics of radioactive element:-

  • Every radioactive element has its own half-life.
  • Half-life period of a radioactive element is independent of all external conditions such as temperature, pressure, and mass.
  • The smaller the half-life period of a radioactive element, the larger is its radioactivity and vice versa.

 

Radioactive decay

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or waves. This process can result in a change in the number of protons, neutrons, or both in the nucleus, leading to the formation of a different element or isotope. Radioactive decay is a random process, and the rate of decay is determined by the half-life of the radioactive substance.

 

Half Life: 

  • It is the time interval in which the mass of a radioactive substance or the number of its atoms is reduced to half of its initial value.
  • It is represented by T1/2

Relation between Half Life and Decay constant :

  • Half life (T1/2) and decay constant (λ) are related as,
  • T1/2 = 0.693/λ

where,

  • n = t/t1/2
  • t = total time period
  • t1/2 = half life period
  • N/N0 = Fraction of radioactive substance left

Measurement of radioactivity:

  • 1 Curie – 3.7 x 1010 disintegration/second(decay/second)
  • 1 Rutherford = 106 disintegration/second(decay/second)
  • Bacquerel – SI unit of radioactivity
  • 1 bacquerel = 1 disintegration/second
  • Radioactivity of the radioactive substance is measured by an instrument called Gieger Muller Counter.

 

Types of radioactive decay

 

 

 

 

Alpha decay 

Alpha decay is a type of radioactive decay in which an unstable nucleus emits an alpha particle, which is a helium nucleus consisting of two protons and two neutrons. The parent nucleus loses two protons and two neutrons during this process, resulting in the formation of a new, lighter nucleus. Alpha decay is commonly observed in heavy elements such as uranium and radium.

 

beta decay

Beta Decay: Beta decay is a type of radioactive decay in which an unstable nucleus emits a beta particle, which is an electron or a positron. In beta-minus decay, a neutron in the nucleus is converted into a proton, releasing an electron and an antineutrino. In beta-plus decay, a proton in the nucleus is converted into a neutron, releasing a positron and a neutrino. Beta decay is commonly observed in elements such as carbon-14 and iodine-131.

 

gamma decay

Gamma Decay: Gamma decay is a type of radioactive decay in which an unstable nucleus emits a gamma ray, which is a high-energy photon. Gamma decay usually occurs after alpha or beta decay and is a way for the nucleus to release any excess energy. Gamma rays are often used in medical imaging and radiation therapy, as they can penetrate through the body and produce detailed images of internal structures.

 

Nuclear reaction

A nuclear reaction is a process that changes the nucleus of an atom, resulting in the formation of a new element. Nuclear reactions involve the rearrangement of subatomic particles, such as protons and neutrons, within the nucleus of an atom, resulting in the formation of new isotopes or elements.

Nuclear reactions can be either natural or artificial. Natural nuclear reactions occur spontaneously in certain isotopes and are responsible for the decay of radioactive materials. Artificial nuclear reactions are induced by bombarding a target nucleus with high-energy particles such as protons, neutrons, or alpha particles.

Nuclear reactions can release a tremendous amount of energy, which can be harnessed for a variety of applications, including nuclear power plants and nuclear weapons. The study of nuclear reactions and the properties of atomic nuclei is known as nuclear physics.

 

Mass defect and binding energy

The mass defect refers to the difference between the mass of a nucleus and the sum of the masses of its individual protons and neutrons. This is due to the fact that some of the mass of the nucleus is converted into energy according to Einstein's famous equation E = mc², where E is the energy, m is the mass and c is the speed of light.

The binding energy of a nucleus is the energy required to break it up into its individual nucleons (protons and neutrons). It is also the energy released when a nucleus is formed from its individual nucleons. The binding energy is a measure of the stability of the nucleus; the higher the binding energy, the more stable the nucleus.

The binding energy per nucleon is a useful measure of nuclear stability, as it takes into account the fact that the binding energy increases with the number of nucleons in the nucleus. Generally, nuclei with high binding energies per nucleon are more stable than those with lower binding energies per nucleon.

The mass defect and binding energy are related by the equation E = mc², where E is the binding energy, m is the mass defect and c is the speed of light. The mass defect can be calculated from the difference between the mass of the nucleus and the sum of the masses of its individual protons and neutrons, while the binding energy can be calculated from the mass defect using the above equation.

Nuclear reactions involve changes in the structure of the atomic nucleus, such as the addition or removal of protons and neutrons, or the splitting of a heavy nucleus into two lighter nuclei (nuclear fission), or the combining of two lighter nuclei to form a heavier nucleus (nuclear fusion). These reactions can release large amounts of energy, which can be harnessed for power generation in nuclear reactors or in nuclear weapons.

 

Nuclear fission

Nuclear fission is a nuclear reaction in which the nucleus of an atom is split into two or more smaller nuclei, along with the release of a large amount of energy. This reaction is typically induced by bombarding a heavy nucleus, such as uranium-235 or plutonium-239, with neutrons.

When the heavy nucleus captures a neutron, it becomes unstable and splits into two smaller nuclei, releasing additional neutrons and a large amount of energy in the form of heat and gamma rays. These released neutrons can then go on to collide with other heavy nuclei, causing a chain reaction that can lead to a massive release of energy.

Nuclear fission has both peaceful and destructive applications. In nuclear power plants, it is used to generate electricity by producing heat, which is used to turn water into steam and power turbines. In nuclear weapons, it is used to create a powerful explosion through an uncontrolled chain reaction.

 

Nuclear reactors

·         Nuclear reactors operate on the principle of nuclear fission, the process in which a heavy atomic nucleus splits into two smaller fragments.

·         It is a device that is used to produce electricity and permits a controlled chain nuclear reaction.

 

Substance

Uses 

235U

It is used as fuel.

Heavy water

Used as moderator (to slow down neutrons)

Control rods 

It is used to absorb neutrons

 

Nuclear fusion

Nuclear fusion is a process in which two atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy in the process. This process is the opposite of nuclear fission, where a heavy nucleus is split into two smaller nuclei.

In nuclear fusion, the positively charged nuclei must overcome their electrostatic repulsion to come close enough for the strong nuclear force to take over and bind them together. This requires very high temperatures and pressures, typically found in the cores of stars and in hydrogen bombs.

One of the most promising applications of nuclear fusion is in the development of fusion reactors as a source of clean, sustainable energy. Unlike nuclear fission reactors, which produce nuclear waste and have the potential for catastrophic accidents, fusion reactors use hydrogen as fuel and produce only helium as waste. However, achieving sustained fusion reactions on Earth has proven to be very difficult, and there are still many scientific and engineering challenges to be overcome before fusion can become a practical energy source.

 

Nuclear fusion 

Nuclear fission 

  • It is the process in which two or more small nuclei fuse together to form a single heavy nucleus.
  • This reaction takes place at an extremely high temperature, therefore this reaction is known as a thermonuclear reaction. .
  • It is the process in which a heavy nucleus splits up into two nuclei of nearly comparable masses or lighter nuclei.
  • It is accompanied by the emission of neutrons along with a large amount of energy.

 

 Uses of radiation

Radiation has various uses in different fields, including:

1. Medical: Radiation is used for diagnostic and therapeutic purposes in medicine. X-rays, CT scans, and PET scans use ionizing radiation to image internal structures of the body. Radiation therapy is also used to treat cancer.

2. Energy: Nuclear power plants use nuclear fission to generate electricity. In nuclear fusion, the energy released from the reaction can potentially provide an unlimited source of clean energy.

3.  Agriculture: Radiation is used in agriculture to create new plant varieties that are resistant to diseases, pests, and environmental stressors.

4.   Industry: Radiation is used in industrial processes to measure the thickness of materials, detect flaws in metals, and sterilize medical equipment and food products.

5.  Research: Radiation is used in research to study the structure and behavior of molecules, atoms, and subatomic particles. It is also used to determine the age of artifacts and geological samples through radiocarbon dating and other techniques.

6.  Security: Radiation detection equipment is used for security purposes to detect and prevent the illicit transport of radioactive materials.