The Atomic Nucleus Fission And Radioactivity

Atomic Nucleus Fission and Radioactivity

Atomic Nucleus

  • Protons and Neutrons:

    • Protons (+ve charge, 1 atomic unit of mass) and neutrons (neutral charge, ≈ 1 atomic unit of mass) are fundamental particles found in the nucleus.
  • Mass Number and Atomic Number:

    • Mass Number (A): Total number of protons and neutrons in the nucleus.
    • Atomic Number (Z): Number of protons in the nucleus.
  • Isotopes and Isobars:

    • Isotopes: Same element with different numbers of neutrons (different mass numbers).
    • Isobars: Different elements with the same mass number.
  • Nuclear Forces:

    • Strong Nuclear Force: Overcomes electrostatic repulsion between positively charged protons, keeping the nucleus intact.
    • Weak Nuclear Force: Involved in radioactive decay processes.
  • Nuclear Size and Density:

    • Nuclei are very small compared to atoms, yet extremely dense.
    • Nuclear density is independent of the size of the nucleus.

Nuclear Reactions

  • Nuclear Fission:

    • Process: Splitting of heavy atomic nuclei into smaller ones, releasing large amounts of energy.
    • Energy Released: Chain reaction can release enormous energy in a short time, as seen in nuclear weapons and nuclear reactors.
    • Chain Reaction: Fission of one nucleus triggers fission of other nearby fissile nuclei, creating a self-sustaining reaction.
    • Critical Mass: Minimum amount of fissile material needed to sustain a chain reaction.
  • Nuclear Fusion:

    • Process: Combining two or more light atomic nuclei into a heavier one, releasing vast amounts of energy.
    • Energy Released: Even greater than in fission, potential for future sustainable energy sources.
    • Fusion in Stars: Powers stars by combining hydrogen nuclei to form helium.

Radioactivity

  • Types of Radioactive Emissions:

    • Alpha Particles (α): Helium nuclei consisting of 2 protons and 2 neutrons, emitted by heavier radioactive elements.
    • Beta Particles (β): High-energy electrons or positrons (anti-electrons) emitted during nuclear transformations.
    • Gamma Rays (γ): High-energy photons emitted from excited atomic nuclei.
  • Radioactive Decay:

    • Spontaneous decay of unstable atomic nuclei, transforming them into more stable forms.
    • Decay rates are characteristic of each radioactive element.
  • Half-life:

    • Time taken for half of the radioactive atoms in a sample to decay.
    • Used to determine the age of radioactive materials and to measure decay rates.
  • Uses of Radioactivity:

    • Medicine: Radiotherapy (cancer treatment), medical imaging (X-rays, CT scans, PET scans).
    • Carbon dating: Used in archaeology and geology to determine the age of ancient materials.
    • Nuclear power: Controlled nuclear reactions generate significant amounts of electricity.

Effects of Nuclear Radiation

  • Ionizing Radiation:

    • Radiation with enough energy to remove electrons from atoms, causing them to become electrically charged ions.
    • Harmful to living tissues, can damage DNA and lead to health issues.
  • Radiation Sickness, Mutations, and Cancer:

    • Severe radiation exposure can cause radiation sickness, with symptoms ranging from nausea to organ damage or death.
    • Can induce genetic mutations and increase the risk of cancer development.
  • Radiation Safety Measures:

    • Shielding: Using materials (e.g., lead) to block radiation.
    • Time: Limiting the amount of time spent in radioactive environments.
    • Distance: Maintaining appropriate distance from radiation sources.

Applications of Nuclear Technology

  • Nuclear Power Plants:

    • Fission reactors: Use controlled nuclear fission to generate electricity.
    • Fusion reactors (still under research): Have the potential to provide abundant, clean energy through nuclear fusion.
  • Medical Imaging:

    • X-rays: Widely used for diagnostic imaging, such as bone fractures.
    • CT (Computed Tomography) scans: Provide detailed cross-sectional images.
    • PET (Positron Emission Tomography) scans: Reveal metabolic activity and aid in diagnosing certain diseases.
  • Radiotherapy in Medicine:

    • Uses controlled radiation doses to target and destroy cancer cells.
  • Carbon Dating:

    • Determines the age of organic materials by measuring the amount of carbon-14 present, useful in archaeology and paleontology.
  • Industrial Radiography:

    • Nondestructive testing technique using gamma rays or X-rays to inspect materials for internal flaws and defects.

Nuclear Waste Management

  • Radioactive Waste Disposal:
    • Deep geological repositories: Underground facilities designed to safely store radioactive waste over extended periods.
    • Long-term Safety: Ensuring the safety and security of radioactive waste storage over thousands of years is a significant challenge.