Why are isotopes important?
The term "isotopes" refers to atoms of an element that have the same quantity of protons but differ in the number of neutrons they possess.
Isotopes of an element all have the same chemical behavior, but the unstable isotopes undergo spontaneous decay during which they emit radiation and achieve a stable state.
This property of radioisotopes is useful in food preservation, archaeological dating of artifacts and medical diagnosis and treatment.
Use as a 'tracer' to determine where a drug is metabolized in the human body. This is possible because although an isotope has a detectable different nuclear structure it behaves the same chemically.
Use the radiation emitted by isotopes as they decay to treat tumors in cancer patients.
Radio-isotopes are a convenient portable source of radiation for the purposes of conducting Non-Destructive-Examinations of safety critical structures.
Fissile material can be separated from non-fissile material to construct a nuclear device (bomb). For uranium this can be done by reacting the uranium with fluorine to get uranium hexa-fluoride. The uranium hexa-fluoride has a relatively low boiling point and can be centrifuged in its gaseous state. When centrifuging has been performed many times the fissile and non-fissile isotopes of uranium become separated.