Nuclear Reactions

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Welcome to class! 

In today’s class, we will be talking about nuclear reactions. Enjoy the class!

Nuclear Reactions

CONTENT

• Nuclear Fusion and Nuclear Fission with Example
• Effects and Application of Radioactivity
• Comparison of Nuclear Reaction and Ordinary Chemical Reactions

Nuclear reaction

This is the spontaneous emission of radiation that involves the nuclei of a radioactive element.

Nuclear fusion

This is the process in which two or more light nuclei of elements combine together to form a heavier nucleus with the release of both energy and radiation.

This process is used to produce a hydrogen bomb, it is also believed to be the source of energy of the sun and stars.

Nuclear fission

This is the process in which the nucleus of a heavy element is split into two nuclei of nearly equal mass with a release of energy and radiation. The process is used to produce an atomic bomb.

Evaluation

1. What is the principle of the atomic bomb?
2. Write short notes about

• Nuclear fission
• Nuclear fusion

Effect of radioactivity

1. It causes changes in cell structure and body chemistry
2. It leads to anaemia, cancer, leukaemia and genetic mutations, even death

The thick blocks of lead, iron and high-density concrete can be used to get shielded from the harmful effect of radioactive rays.

Application of radioactivity

1. Sterilization
2. Medical uses
3. Industrial uses
4. Agricultural uses
5. As radioactive tracers
6. Used for dating techniques

Differences between nuclear reaction and chemical reactions

Artificial transmutation

This is the process of transmutation of an element by bombarding it with fast-moving atomic particles e.g neutrons, protons, deuterons and alpha particles.

¹⁴₇N   + ¹₀n      →          ¹⁴₆C  + ¹₁P

N.B: If the nucleus being bombarded is heavy it captures the neutron to produce an isotope of the original element

⁵⁹₂₇Co    +   ¹₀n         →               ⁶⁰₂₇C_O

Binding energy

If mathematical calculations are carried out between the parent nucleus and daughter nuclei together with neutrons and protons on either nuclear fusion or nuclear fission, it will be found that the values differ.

The loss of mass is known as the mass defect and can be accounted for by Albert Einstein’s theory of relativity.

E = MC²

E is energy in joule (j)

Radioactive disintegration

This is the process by which radioactive elements decay spontaneously to release radiation.

During this process, there is usually transmutation of an atom. That is the formation of the daughter nucleus from the disintegrating nucleus.

Alpha decay

When atom losses ά particles during disintegration, the atomic number and atomic mass of the atoms is reduced by 2 and 4 respectively.  This can be represented as

^A_ZK           →                   ^A-4 _Z-2L    +  ⁴ ₂He

 

e.g.   ²³⁸ U             →              ²³⁵Th    +  ⁴ ₂He

Beta-decay

During beta decay, the atomic number of the atom increases by one unit, but the atomic mass number remains unaltered.

^AK         →                 ₍₂₊₁₎L    + _-1 e

 

²³⁴T         →             ²³⁴Pa  + _-1 e

Gamma decay

Gamma rays usually accompany the emission of either alpha or beta particles e.g.

²³⁴ Th      →             ²³⁴Pa   + _-1e + y

Radioactive decay series

Sometimes, if the nuclei of the new elements produced during radioactive decay are not stable, the disintegration continues until a stable nucleus is finally produced e.g. Uranium series, the thorium series and the actinium series.

M is the loss in mass in kilogram (kg) and C is the velocity of light in ms-1

General evaluation

1. Define the following with an example each (a) Nuclear Fission       (b) Nuclear Fusion
2. (a) State two effects of radioactivity.     (b) State two differences between nuclear reaction and chemical reaction.

Reading assignment

New School Chemistry by O. Y. Ababio pages 304-310.

Weekend assignment

1. Examples of radioactive elements are except (a) Uranium (b) Polonium (c) Thorium (d) Oxygen
2. ²³⁵ ₉₂U   + ¹n →  ^{141 ­} ₅₆Ba +  ⁹² ₃₆Kr  + 3 ¹ ₀n . The nuclear reaction represents (a) nuclear fission (b) nuclear fusion (c) oxidation reaction (d) esterification reaction.
3. ²³⁸ ₉₂U           →        ²³⁴ ₉₀Th  +   A.    In the equation, A represents (a) hydrogen (b) beryllium (c) helium (d) oxygen
4. Chain reaction helps during the preparation of ____ (a) Solar bomb (b) atomic bomb (c) hydrogen bomb (d) nuclear fusion
5. ²³ ₁₁Na  + ₀¹n      →   ²⁴₁₁Na The reaction represents (a) artificial radioactivity (b) Natural radioactivity (c) Nuclear fission (d) Binding energy.

Theory

1. Explain briefly the principle of the operation of a nuclear power plant
2. State five (5) uses of radioactivity

 

In our next class, we will be talking about Simple Molecules and their Shapes.  We hope you enjoyed the class.

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