P7: Radioactivity

• Radioactivity

  The process by which unstable atomic nuclei lose energy by emitting radiation
• Main types of radiation

  • Alpha radiation
  • Beta radiation
  • Gamma radiation
• Alpha particle

  Consists of 2 protons and 2 neutrons (essentially a helium nucleus)
• Alpha radiation

  Decreases the atomic number by 2 and the mass number by 4
• Beta particle

  A high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus
• Beta radiation

  Increases the atomic number by 1 (if it's a beta-minus particle) without changing the mass number
• Gamma radiation

  Electromagnetic radiation of high frequency and high energy, emitted from the atomic nucleus
• Gamma radiation does not change the atomic number or mass number of the nucleus
• Half-life

  The time taken for half the nuclei in a sample of a radioactive substance to decay
• Calculating remaining quantity of a radioactive substance

  Remaining quantity = Initial quantity × (1/2)^number of half-lives
• Ionizing radiation

  Radiation that carries enough energy to liberate electrons from atoms or molecules, thereby ionizing them
• Alpha particles

  • Can be stopped by a sheet of paper or human skin
• Beta particles

  • Can be stopped by a few millimeters of aluminum
• Gamma rays

  • Can be reduced by thick lead or several centimeters of concrete
• Geiger-Müller tube

  A device used to detect and measure ionizing radiation
• Background radiation

  The ionizing radiation present in the environment that originates from natural and artificial sources
• Sources of natural background radiation

  • Cosmic rays
  • Radon gas
  • Natural elements like uranium
• Radioactive isotope

  An isotope of an element that is unstable and undergoes radioactive decay
• Radioactive decay is random because it is impossible to predict exactly when a particular nucleus will decay
• Nuclear fission

  The process of splitting a large atomic nucleus into smaller nuclei with the release of energy
• Nuclear fusion

  The process of combining two light atomic nuclei to form a heavier nucleus with the release of energy
• High levels of radiation can cause damage to living tissues, potentially leading to radiation sickness, cancer, and genetic mutations
• Radioactive tracers

  Used in medicine and industry to follow the movement of substances within organisms or systems
• Radiocarbon dating

  Measures the amount of carbon-14 in an artifact to determine its age, based on the known half-life of carbon-14
• Safety measures for handling radioactive materials

  • Using shielding
  • Maintaining a safe distance
  • Minimizing exposure time
  • Using proper protective equipment
• Nuclear fission:

  The splitting / a neutron hitting a large unstable nucleus into two smaller nuclei, releasing energy. After will release a neutron hitting another unstable nucleus, starting a chain reaction.

  
• Induced fission is where a neutron is absorbed by a nucleus and causes it to split
• In a nuclear reactor, control rods (made of boron) control amount of reactions occurring by absorbing neutrons