radioactivity - tendency to decay, emit particles

• radionuclides - radioactive nuclei
• radioisotopes - atoms w/ radioactive nuclei
• alpha radiation - emitting alpha particles (helium-4 nuclei)
  • atomic number decreases by 2
  • atomic mass decreases by 4
• beta radiation - emits electrons from unstable nucleus
  • neutron >> proton
  • atomic number increases by 1
  • atomic mass stays the same
• gamma radiation - emits high-energy photons
  • accompanies other radioactive emissions
  • doesn’t change atomic number/mass
• electron capture - nucleus gains electron from surrounding electron cloud
  • proton >> neutron
  • atomic number decreases by 1
  • atomic mass stays the same

nuclear stability - depends on multiple factors

• neutron-proton ratio - neutron # > proton # to ensure stability in atoms w/ large atomic numbers
  • belt of stability - area in which all stable nuclei are found
  • all nuclei w/ 84+ protons are radioactive
  • nuclei above belt of stability use beta emission >> increases proton #, decreases neutron #
  • nuclei below belt of stability use electron capture, positron emission >> decrease proton #, increase neutron #
  • nuclei with over 84 protons use alpha emission
• radioactive series - aka nuclear disintegration series
  • 3 naturally occurring series end with lead
  • stability not achieved w/ a single emission (needs a series of emissions)
• magic numbers - 2, 8, 20, 28, 50, 82 protons; 2, 8, 20, 28, 50, 82, 126 neutrons
  • usually more stable when w/ these numbers