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 particular form of an element. The atoms of one isotope of an element differ from those of another isotope of the same element primarily in the number of neutrons in their nuclei. (They all have the same number for both protons and electrons.)