Basics of Radioactivity Quiz

Basics of Radioactivity

• Radioactivity involves the disintegration of unstable atomic nuclei, emitting energy and transforming into new elements.
• Henri Becquerel discovered radioactive emissions from uranium compounds in 1896.
• Radioactive decay transitions from a parent nuclide to a daughter nuclide, with an energy difference linked to decay energy.

Types of Radioactive Decay

• Alpha Decay:
  • Parent nuclei emit alpha particles (4,2α), resulting in a decrease of atomic mass (−4) and atomic number (−2).
• Beta Decay:
  • Occurs in neutron-rich nuclides, emitting beta particles (β−) with a gain of one atomic number (+1); atomic mass remains constant.
• Positron Emission:
  • Proton-rich nuclides emit positrons, converting a proton into a neutron; positrons annihilate with electrons, producing gamma radiation.
• Electron Capture:
  • Nucleus absorbs an inner electron, converting a proton into a neutron and releasing gamma rays.
• Gamma Emission:
  • Involves energetic transitions between excited states without changing atomic mass or number.

Characteristics of Radionuclides

• Alpha particles are monoenergetic; Beta particles exhibit an energy spectrum.
• Electron capture and positron emission produce characteristic X-rays.
• Radionuclides used in medicine include 125I, 123I, 201Tl, 67Ga, and 111In.

Activity and Decay Constants

• Activity (A(t)) represents the number of disintegrations per second for a radioactive substance.
• Activity is defined as A(t) = λN(t), where λ is the decay constant.
• Activity of parent nuclei decreases exponentially over time: A(t) = A(0)e^{-λt}.

Nuclide Transformation

• Positron and beta emissions, along with electron capture, change the original element to a new element.
• Alpha emissions are less common in medical applications but have therapeutic uses.

Summary of Decay Properties

• Radon nuclides demonstrate different decay mechanisms, including associated energy emissions and changes in atomic configuration.