Radioactivity

Radioactivity is the process by which the atoms of a naturally occurring substance emit particles or radiation due to the spontaneous disintegration of their atomic nuclei.

Types of Radiation

1. Alpha (α) particles
2. Beta (β) particles
3. Gamma (γ) rays

Comparison of Radiation Types

Advantages of Radioactive Substances

1. It is used in medical treatments, such as treating malignant growths similar to X-rays.
2. Serves as the primary source of nuclear fuel for energy generation.
3. Radioactive isotopes are useful in tracer techniques.
4. Help in estimating the age of archaeological findings.

Disadvantages of Radioactive Substances

1. Radiation exposure destroys living tissue cells.
2. Can disrupt chemical reactions in blood cells, potentially leading to fatal consequences.

Artificial Radioactivity

Artificial radioactivity occurs when an element becomes radioactive through exposure to radiation, such as neutron irradiation. This process can happen either accidentally or intentionally.

Examples of Artificial Radioactivity Reactions

• Reaction 1:
  \[\alpha_{2}^{4} + N_{7}^{14} \rightarrow F_{9}^{18} \rightarrow O_{8}^{17} + H_{1}^{1} + \text{energy}\]
• Reaction 2:
  \[\alpha_{2}^{4} + Al_{13}^{27} \rightarrow P_{15}^{30} + n_{0}^{1} \rightarrow Si_{14}^{30} + e_{1}^{0} + \text{energy}\]
• Reaction 3:
  \[n_{0}^{1} + Li_{3}^{6} \rightarrow H_{1}^{3} + He_{2}^{4} + \text{energy}\]
• Reaction 4:
  \[n_{0}^{1} + Mg_{11}^{24} \rightarrow Na_{11}^{24} + P_{1}^{1} + \text{energy}\]
• Reaction 5:
  \[\alpha_{2}^{4} + Be_{4}^{9} \rightarrow C_{6}^{12} + n_{0}^{1} + \text{energy}\]
• Reaction 6:
  \[n_{0}^{1} + Co_{27}^{59} \rightarrow Co_{27}^{60} + \text{energy}\]

Artificially Produced Isotopes

Isotopes can also be produced artificially by bombarding elements with neutrons, protons, or deuterons. Examples include:

• Reaction 7:
  \[S_{10}^{34} + n_{0}^{1} \rightarrow S_{10}^{35} + \text{energy}\]
• Reaction 8:
  \[Br_{35}^{79} + n_{0}^{1} \rightarrow Br_{35}^{80} + \text{energy}\]

Radioisotopes

Artificially produced isotopes are often unstable and decay by emitting alpha (\(\alpha\)), beta (\(\beta\)), or gamma (\(\gamma\)) radiation. These unstable isotopes are known as radioisotopes. They are created through neutron, proton, or deuteron bombardment of elements.

Binding Energy

Binding energy is the energy required to split an atomic nucleus. It is given by the equation:

\[ E = \Delta m C^2 \]

Where:

• \( E \) = Energy (Joules)
• \( \Delta m \) = Mass defect (kg)
• \( C \) = Speed of light (m/s)

Nuclear Fusion

Nuclear fusion is the process where two or more light nuclei combine to form a heavier nucleus, releasing a significant amount of energy. An example of fusion is:

\[ ^2_1H + ^1_0n \rightarrow ^4_2He + n + \text{Energy} \]

Nuclear Fission

Nuclear fission occurs when a heavy atomic nucleus splits into two nearly equal parts, releasing a large amount of energy and additional neutrons. An example is:

\[ ^{235}_{92}U + ^1_0n \rightarrow ^{141}_{56}Ba + ^{92}_{36}Kr + 3(^1_0n) \]

Half-Life

The half-life (\( T_{1/2} \)) of a radioactive element is the time taken for half of its atoms to decay. The SI unit is seconds (s). It is given by:

\[ T_{1/2} = \frac{\ln 2}{\lambda} = \frac{0.693}{\lambda} \]

Decay Constant (λ)

The decay constant (\( \lambda \)) is the instantaneous rate of decay per unit atom of a radioactive substance. The relationship between half-life and decay is:

\[ N = N_0 \left( \frac{1}{2} \right)^{\frac{t}{T_{1/2}}} \]

Where:

• \( T_{1/2} \) = Half-life
• \( t \) = Time period
• \( N_0 \) = Initial quantity of the substance
• \( N \) = Final quantity remaining

Application of Radioactivity

1. Used in agriculture as radioactive tracers.
2. Applied in medicine to treat cancer patients and sterilize surgical equipment.
3. Utilized in industries to detect defects in metals, inspect welded joints, and check metal fatigue.