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)