Welcome to the Community College of the Air Force (CCAF). Our college is a federally-chartered degree-granting institution that serves the United States Air Force's enlisted total force.
Isotopes of an element have nuclei with the same number of protons (the same atomic number) but different numbers of neutrons. Therefore, isotopes have different mass numbers, which give the total number of nucleons-the number of protons plus neutrons.
Stable Isotope Principles. An isotope is an atom whose nuclei contain the same number of protons but a different number of neutrons. Isotopes are broken into two specific types: stable and unstable. These unstable isotopes are commonly referred to as radioactive isotopes.