Nuclear Chemistry – Introduction, Questions and Answers

The disclosure of radioactivity helped in the creation and development of nuclear chemistry in the early twentieth century. In the mid of 20^th  century, new findings and the 2^nd World War ushered in the Nuclear Age. From power generation to war damage, nuclear chemistry had shown huge potential. The wide growth of the area has brought about a wide variety of nuclear chemistry topics – like nuclear chemistry, nuclear radiations, the uses of nuclear chemistry, artificially simulated nuclear reactions (fission and fusion) etc.

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Nuclear Chemistry 

Nuclear chemistry is the study of the chemical and physical properties of elements that deal with reactions that happen inside the nuclear structure. Which is also known as nuclear reaction. Modern nuclear chemistry also referred to as radio chemistry, has become high knowledge base in its applications,  from the study of element formation in space to the design of radio pharmaceuticals for diagnostic medicine. In fact, the chemical technology developed by these chemists has become so important that geologists,  biologists and physicists are using nuclear chemistry as a common tool in their fields.

Nuclear chemists can be seen in a variety of research applications, like nuclear imaging and nuclear technology. The chemists usually work to improve the efficiency and safety of nuclear energy sources and the way radioactive materials are disposed of and stored.

Nuclear chemists carry out applied research, basic research and theoretical research. They often work in the labs and are responsible for the operation, maintenance, and repair of state-of-the-art equipment. They are also responsible for the maintenance of sample preparation materials and equipment, and for the safe use and disposal of samples and other substances used in the lab.

Marie Curie, who was the founder of nuclear chemistry, was along with Antoine Henri Bekrel’s found that photographic film can give out light that can be exposed even when uranium minerals are covered in black paper. Using an electrometer which was used to measure the electrical conductivity of air (the predecessor of the Geiger counter) which was invented by her husband Pierre and his younger brother Jack, Curie was able to prove that thorium also produces these rays. This process was called radioactivity by her.

What Is Nuclear Chemistry?

Nuclear chemistry is a subset of chemistry which deals with the study of changes in the nucleus of atoms of elements. These nuclear changes are a source of radioactivity, and nuclear power. The energy produced from the nuclear reactions has tremendous applications. Nuclear chemistry is also termed radiochemistry, which is the study of the elements composing the universe, design, and development of radioactive drugs for medicinal uses, and many other scientific applications.

Nuclear Radiations

Nuclear radiation is the photons and particles that are generated during nuclear reactions. The particles emitted in nuclear reactions have an energy that is huge enough to knock electrons from atoms and molecules, causing them to  ionize. Hence, nuclear radiation is also referred to as ionizing radiation.

Nuclear radiations consists of alpha rays, beta rays, and gamma rays. Nuclear reactions give out ionizing subatomic particles, like muons, positrons, alpha particles, neutrons, beta particles, mesons and cosmic rays. For example: during the fission reaction of Uranium-235 , the nuclear radiation that is emitted has gamma-ray along with photons and neutrons. 

Types of Radiations

Alpha Radiation:

Alpha rays are dense particles and have a very little range, so they don’t very far. This means that these particles cannot penetrate even a piece of paper. Alpha particles outside the body cannot even pass through the skin surface of a human body. However, inhaling or ingesting substances that emit alpha particles can expose vulnerable tissues like that to the lungs. Hence, high-level radon in your home is considered a problem for this reason.

Alpha radiation is the release of alpha particles when an atom goes through radioactive decay. An alpha particle consists of 2 protons and 2 neutrons and is same as the Helium-4 atom. Thus, the resulting element has an atomic number less by 2 units and an atomic mass less by 4units than that of the originating element. Example: Uranium-238 undergoes alpha decay in the manner shown in the following equation:

²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He

Beta Radiation:

Beta particles can travel a little more than alpha particles. You can use a relatively smaller protective covering to stop them. They can get into human body, but they can’t penetrate through it completely. To make use of beta particles in medical imaging,  they must be released through substances injected into the body. If radioactive substances can be introduced into tumors, beta particles will also be used in treating cancer.

Beta radiations contains stream of high-speed electrons. Beta-decay are of 2 types –beta plus and beta minus. In beta plus decay, the nucleus emits a positively charged electron (positron) and a proton that is regenerated into a neutron (neutrino). In beta minus decay, the nucleus gives out a neutron that is changed into a proton (antineutrino) and an electron.

Beta minus decay: ¹n → ¹p⁺ + ⁰_-1β^– + v̅

Beta plus decay: ¹₁p⁺ → ¹₀n + ⁰₁β + v

¹²₇N ⟶ ₆¹²C + ⁰₁β⁺

¹⁴₆C ⟶ ¹⁴₇N + ⁰_-1β

Gamma Radiation:

Gamma rays and X-rays are highly penetrating EM or electromagnetic radiation that can go in through the body. They are proven to be useful in a medicine-to find if the bones are broken, where the cavities are, or to identify a tumor. Shields made of high-density substances such as concrete and lead are used to avoid exposure to sensitive internal organs and those who may have to handle this type of radiation.

Gamma radiation (γ) does not have any particles. Instead, it consists of photons of energy being generated from an unstable radioactive nucleus. Gamma rays are electromagnetic emissions of short wavelengths and have no charge or mass. These rays represent the loss in energy while the rest of the nucleons undergo stable rearrangements, and thus, gamma rays come with other radioactive emissions. Example:

²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He + 2₀⁰γ

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Nuclear Fission

Nuclear Fission is a simulated nuclear reaction where a heavy nucleus splits into 2 lighter nuclei. Fission was discovered by stuffing a sample of Uranium-235 with neutrons, which resulted in the formation of lighter elements like Barium. In a distinctive nuclear chain reaction, each dividing nucleus releases more than a single neutron, which, in turn, clashes with neighboring nuclei and induces a succession of self-sustaining nuclear fission reactions. The fission rate escalates geometrically with each generation of events.

Nuclear Fusion

Nuclear Fusion is a simulated nuclear reaction in which two or more nuclei of elements combine to produce a heavier and more stable nucleus. The initiation of the fusion process needs very high temperatures, which are got from nuclear fission reactions. Nuclear Fusion generates explosive amounts of energy, which is the source of power for the sun and all the stars. E.g: fusion of deuterium-deuterium (D-D) and fusion of deuterium-tritium (D-T).

2 ²₁H → ³₂He + ¹₀n

²₁H + ³₁H → ⁴₂He + ¹₀n

Applications of Nuclear Chemistry

Agriculture

• Breeding and mutation in plants to get improved nutrition and food security.
• Management of fertilizer use through Radio labelling.
• Controlling insect populations.

Consumer products

• Smoke detectors, non-stick materials, clocks, and watches utilize radioisotopes.

Food

• Food irradiation with gamma rays to avoid spoilage and improve shelf-life.
• Pest control.

Industry

• Radioactive tracers find use in industrial processes.
• Inspection of instruments.
• Carbon dating.
• Nuclear desalination of water.

Medicine

• MRI scans, CT scans, and X-rays for diagnosis.
• Radioactive Iodine is made use of to treat cancers.
• Sterilization of medical instruments.

Transport

• Nuclear-powered submarines and ships.
• Radioisotope thermal generators for electricity production in space missions.

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Nuclear Chemistry: Questions and Answers 

1. How are nuclear reactions different from chemical reactions?

Ans:

• In nuclear reactions, the nuclei of a single atom emit particles or rays,whereas, in chemical reactions, bonds are broken and formed between two distinct atoms.

• Atoms  undergo rearrangements but themselves remain unchanged in chemical reactions. On the contrary, nuclear reactions involve a change in the nuclear composition of the element itself and hence, a transformation of one atom to another type.

• The chemical reactions involve only the valence electrons where as the nuclear reactions includes all electrons, protons, and neutrons.

• Chemical reactions cause small energy changes. But nuclear reactions are accompanied by significant changes in energy.

• The factors influencing the rate of a chemical reaction include temperature, reactant, pressure, product concentration and the presence of catalysts. whereas, nuclear reactions are unaffected by any of these external factors, and their rate of change can vary between a few milliseconds and millions of years.

 2. What is transmutation in nuclear chemistry?

 Ans: The transition of an atom of one element into an atom of another element through nuclear reactions is known as nuclear transmutation. Transmutation are of two types based on how it occurs –

• when the nucleus of an atom naturally decays radioactively, or when the nucleus reacts with another particle.
• when nuclear transmutation is induced by bombarding the nuclie with high volume particles.

3. How can radiation Harm the Human body?

Ans: Radiation can be extremely dangerous if used incorrectly and for wrong purposes without the consultation of a skillful person. Radiation is given a bad public representation because some people try to use the effects of radiation to harm others.

4. What are the few positive effects of nuclear chemistry? 

Ans: They can be used in the field of medicine to detect cavities and tumors in a patient. They are also used for Radiation treatments for cancer patients.

5. What is residual nuclear reaction?

Ans: Residual radiation is primarily the fallout that occurs from weapon debris, fission products, etc that occurs after a nuclear explosion/reaction.

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Nuclear Chemistry: Quiz

1. Who was the first person to win Nobel Prizes in two fields ?

a) Ernest Rutherford

b) Henri Becquerel

c) Marie Curie

d) Rosalind Franklin

Ans: (c) Marie Curie

2. Beta radiation is the

a) transmutation of a neutron into a proton and electron with the emission of proton.

b) transmutation of a proton into a neutron and electron with the emission of electron.

c) transmutation of a proton into a neutron and electron. The proton is emitted.

d) transmutation of a neutron into a proton and electron. The electron is emitted.

Ans (d) transmutation of a neutron into a proton and electron. The electron is emitted.

3. The atomic number decreases by two during _________ radiation?

a) alpha

b) beta

c) gamma

d) none of the choices

Ans (a) alpha

4. X-rays are an example of what type of radiation

a) alpha

b) beta

c) gamma

d) transmutation

Ans (c) gamma

5. The atomic number increases by one during ________ radioactive decay?

a) alpha

b) beta

c) gamma

d) none of the choices

Ans (b) beta

6. After three half-lives, ____________ fraction of the original radioactive isotope remains?

a) 1/16

b) 1/2

c) 1/4

d) 1/8

Ans (d) 1/8

7. The ________ is the source of energy produced by the sun.

a) burning of fossil fuel.

b) fission of uranium.

c) fusion of hydrogen.

d) none of the choices

Ans (c) fusion of hydrogen

8. During Nuclear fission:

a) nucleus of an atom is fused with nucleus of another atom.

b) nucleus of an atom is aroused to split into fragments by some source.

c) nucleus of an atom loses a proton to release enormous energy.

d) nucleus of an atom spontaneously splits into fragments.

Ans (b) nucleus of an atom is aroused to split into fragments by some source.

9. In nuclear fusion

a) large unstable nuclei are fused and split.

b) large unstable nuclei are split, releasing energy.

c) relatively small and stable nuclei are fused together to create a larger atom.

d) relatively small and stable nuclei are split, releasing energy.

Ans (c) relatively small and stable nuclei are fused together to create a larger atom.

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