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.
Isotopes have the same number of protons, but differ in the number of neutrons they carry. The majority of elements have two or more structural variations called isotopes. Isotopes of an element have the same number of protons, but differ in the number of neutrons they contain. Isotopes are not necessarily present in equal amounts in a given element.