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: Different Types of Atoms. Atoms in a chemical element that have different numbers of neutrons than protons and electrons are called isotopes. The atoms in a particular element have an identical number of protons and electrons but can have varying numbers of neutrons.