Half Life

All radioactive elements are subject to devolve into an element of less protons and atomic mass. The amount of time it takes s for half of a sample to devolve is called a half life. Some elements can take numbers of years or centuries to decompose while others can in a matter of seconds. For example, carbon 14's half life is 5730 years. The half life of an isotope can be expressed though a basic exponential algorithm.

http://www.coolmath.com/algebra/17-exponentials-logarithms/13-radioactive-decay-decibel-levels-01

Elements with half lives can be applicable to many functions that we use in our world. It's amazing to think about all that these simple particles can actually accomplish.