Half-Life of Radioactive Isotopes
Choose one of the isotopes from the list below:
Name of your chosen radioactive isotope:___________________________________________________
Convert the half-life that is given in days, into weeks and years. Round your answers to 4 decimal
Half-Life in Days: Half-Life in Weeks: Half-Life in Years:
Moving forward, we will use the half-life in days, so t will be measured in days. Using the formula for
exponential decay (𝐴 = 𝐴0𝑒 𝑘𝑡) and the half-life for your radioactive isotope, calculate k. Make sure to
get your value of k to 8 decimal places.
𝑘 = _______________________
Write an equation for your radioactive isotope plugging in k, but no specific value of t (for example, 𝐴 =
𝐴 = _________________________________
Now, use your equation to find how long it will take for the radioactive isotope to decay to 20% of its
original amount. Round your answer to the nearest tenth.