The Atomic Nucleus Fission And Radioactivity
Atomic Nucleus Fission and Radioactivity
Atomic Nucleus
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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.
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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.
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Isotopes and Isobars:
- Isotopes: Same element with different numbers of neutrons (different mass numbers).
- Isobars: Different elements with the same mass number.
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Nuclear Forces:
- Strong Nuclear Force: Overcomes electrostatic repulsion between positively charged protons, keeping the nucleus intact.
- Weak Nuclear Force: Involved in radioactive decay processes.
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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
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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.
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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
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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.
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Radioactive Decay:
- Spontaneous decay of unstable atomic nuclei, transforming them into more stable forms.
- Decay rates are characteristic of each radioactive element.
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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.
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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
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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.
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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.
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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
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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.
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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.
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Radiotherapy in Medicine:
- Uses controlled radiation doses to target and destroy cancer cells.
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Carbon Dating:
- Determines the age of organic materials by measuring the amount of carbon-14 present, useful in archaeology and paleontology.
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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.