An atom of carbon-14 is unstable, meaning that it can spontaneously transform itself (by radioactive decay) into nitrogen at any instant. The probability that this will actually happen to a specific atom of carbon-14 in the course of a year is only 0.0121 percent, however. In other words, there is a 99.9879 percent chance that any specific atom of carbon-14 will survive another year. Suppose that one million carbon-14 atoms are placed in a container. How many of these atoms are expected to be carbon-14 atoms one year later? The half-life question: How much time will it take for half the atoms to decay?