Ch. 5.1 Nuclear Chemistry

Radioisotope

  • A radioisotope

    • is an isotope of an element that emits radiation

    • can be one or more isotopes of an element

    • includes mass number in its name

  • The atomic symbol of iodine-131, a radioisotope used in the diagnosis and treatment of thyroid disorders, has a mass number of 131 and an atomic number of 53

Natural Radioactivity

  • Radioactivity comes from unstable nuclei, which are

    • found in carbon, hydrogen and elements with atomic numbers 20 and higher

    • defines as nuclei in which the nuclear forces cannot offset the repulsions between the protons

    • radioactive, emitting small particles of energy called radiation to become more stable

  • Radiation may take the form of

    • Alpha (α) particles

    • Beta (β) particles

    • Positrons (β+)

    • Gamma (γ) rays (pure energy)


Stable vs. radioactive isotopes:

  • Stable isotopes do not decay.

  • Radioactive isotopes decay and emit radiation.



  • Types of Radiation

  • Emitted radiation types:

    • Alpha particles (α): identical to a helium nucleus. 42He\frac42He

    • Beta particles (β): high-energy electrons. 0−1e\frac{0}{-1}e

    • Positrons: positively charged electrons (β+) 0+1e\frac{0}{+1}e

    • Gamma rays (γ\gamma ) pure energy, no mass or charge 00γ\frac00\gamma

  • Quick identifiers:

    • Alpha, Beta, Positron, Gamma.

Some Forms of Radiation

Biological Effects of Radiation

  • Ionizing radiation strikes molecules in its path and

    • knocks away electrons in molecules, forming unstable ions such as H2O

    • causes undesirable chemical reactions

    • damages the cells most sensitive to radiation, rapidly dividing cells in bone marrow, skin and reproductive organs, thus causing cancer


Radiation Protection

  • Radiation protection requires

    • paper and clothing for blocking alpha particles

    • a lab coat or gloves for blocking beta particles

    • dense shielding such as lead or concrete to block gamma rays

  • for those working in an environment where radioactive materials are present, exposure should be limited by

    • minimizing the amount of time spent near a radioactive source

    • increasing the distance from the source


    Properties of Radiation



Additional notes on safety, relevance, and context

  • The content emphasizes practical safety in clinical settings where nuclear medicine is used.

  • Ethical and practical implications include responsible handling of radiopharmaceuticals, minimizing patient and worker exposure, and adhering to regulatory guidelines for radiation protection.

  • The material connects to foundational principles of nuclear physics: emission processes, particle types, and shielding design based on penetration depth and interaction with matter.