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.
An isotope is a variant on an element that has a different atomic weight from other variants. Except for the commonest form of hydrogen â which has only a proton â every atomic nucleus in normal matter is made of both protons and neutrons.oo many neutrons can also make an isotope unstable. For example, the commonest form of hydrogen has one proton and no neutrons, but there are two other forms, with one and two neutrons, called deuterium and tritium, respectively.