Physical Science - Chapter 8

Nuclear Changes

8A Radioactive Decay

• ^^Nuclear Change^^: any change that alters the composition of the nucleus in an atom

Discovering Radioactivity

• ^^X-ray^^: used for medical imagery, transportation security, and nondestructive inspection

• ^^Radioactive Decay^^: the naturally occurring, spontaneous change of an unstable isotope to a more stable one by emitting particles or energy or both

• ^^Strong Force^^: an attractive force that holds protons and neutrons together in a nucleus

• Types of Radioactive Decay

  • ^^Alpha Decay^^: a nuclear decay that results in the emission of an alpha particle
  • ^^Beta Decay^^: a nuclear decay that results in the emission of a beta particle
  • ^^Gamma Decay^^: a nuclear decay that results in the emission of gamma rays

• ^^Half-life^^: the time in which half the atoms of a radioactive sample will probably decay

8B: Fission and Fusion

• ^^artificial transmutation^^: a manmade artificial change

• Fission

  • ^^fission^^: a nuclear reaction in which a large nucleus splits into smaller nuclei
  • ^^chain reaction^^: a self-sustaining nuclear fission process in which neutrons produced in one fission reaction trigger more fission events
  • ^^critical mass^^: the smallest mass of fissionable material that can sustain a chain reaction

• ^^fusion^^: a nuclear reaction in which small nuclei combine to form a more massive nucleus

8C: Nuclear Changes - Benefits and Risks

• Using Radiation
  • ^^radiotracer^^: a radioactive isotope used in nuclear medicine to study how an isotope moves through or collects in a certain way
• Effects of Radiation
  • ^^ionizing radiation^^: radiation that is energetic enough to knock electrons out of atoms or molecules; most damaging to living organisms
  • ^^somatic damage^^: any damage to cells that are not involved in reproduction, thus harming the organism but not any future offspring
  • ^^genetic damage^^: any damage done to DNA in cells that can affect growth and reproduction of the cells; can be passed to offspring if it occurs in reproductive cells
• Detecting Radiation
  • ^^Geiger counter^^: a device designed to measure ionizing radiation
  • ^^dosimeter^^: a device used to measure exposure to radiation