AP Chemistry/Nuclear Chemistry

  • Nuclear chemistry is just arithmetic with two variables - charge and mass.
  • proton + electron = neutron
  • 2 protons + 2 neutrons = alpha particle (Helium-4 Nucleus)
  • electron = beta particle
  • energy = gamma ray emission
  • proton = neutron + positron

Nuclear Stability

  • Anything with 83 protons (Bismuth) or more is radioactive. Small stable molecules have a neutron:proton ratio of approximately 1:1. More massive ones have a ratio of 1.5:1.
  • Isotopes can also be radioactive, an example of this is carbon-14 which is used in carbon dating only has 6 protons but is radioactive .

Half Life


The half life of an isotope is time it take for half of a sample to decay. It can vary from very small times(fraction of second) to millions of years. Knowing the half life of a substance allows radioactive dating to be done. The relative abundance of the isotopes in a sample compared to the original abundance can be used to determine the age of the specimen.

  • ln(percent remaining) = -k(time)
  • half-life = ln(2/k)