Week 2 – SS3 Second Term Chemistry Notes

WEEK TWO
TOPIC: 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 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 release of both energy and radiation.
This process is used to produce 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 atomic bomb.

 EVALUATION

• Write short notes about

1. Nuclear fission
2. Nuclear fusion

• What is the principle of atomic bomb.

 Effect of Radioactivity

1. It causes changes in cell structure and body chemistry
2. It leads to anemia, cancer, leukemia 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

• sterilization
• medical uses
• industrial uses
• agricultural uses
• as radioactive tracers
• used for dating techniques

 Differences Between Nuclear Reaction and Chemical Reactions
    Nuclear Reaction             Chemical Reaction
1. Release large amount of energy                Release little amount of energy when                                           compared to that of nuclear reaction
2. It involves nuclei of atoms of radioactive         It revolves the outer most electrons of
elements                         atoms.           
3. This produces different elements              The compound produces contain the same            type of element from the reactants.
4. It produces radiation                No radiation produce
5. Temperature and pressure have no effect         Both temperature and pressure have
on chemical reaction        efects on chemical reaction

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 is carried out between the parent nucleus and daughter nuclei together with neutrons and protons on either nuclear fussion or nuclear fission, it will be found that the values are differed.
The loss of mass is known as mass defect and can be accounted for by Albert Einsteins 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 formation of daughter nucleus from the disintegrating nucleus.

 Alpha Decay
When an 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

 
²³⁴Th 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 is not stable, the disintegration continue 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 above 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