Lesson Plan

Explain radioactive half-life and why decay is a statistical, memoryless process

Define the decay constant and activity, and relate them to half-life

Calculate half-life, decay constant, remaining quantity, or activity using N = N₀e^(−λt) and R = λN

Explain how radiometric dating uses known half-lives to determine age

Solve carbon-14 and uranium-238 dating problems

22.3

"The time in which half of the original number of nuclei decay is defined as the half-life, t_1/2. After one half-life passes, half of the remaining nuclei will decay in the next half-life." "A more precise definition of half-life is that each nucleus has a 50 percent chance of surviving for a time equal to one half-life... the decay of a nucleus is like random coin flipping. The chance of heads is 50 percent, no matter what has happened before." "When an organism dies, carbon exchange with the environment ceases, and 14C is not replenished. By comparing the abundance of 14C in an artifact... with the normal abundance in living tissue, it is possible to determine the artifact's age."