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.
Atoms of an element usually have the same number of neutrons as protons. Atoms of the same element that have a different number of neutrons are called isotopes. Isotopes have the same atomic number but different atomic masses. Atoms of an element share that element's chemical and physical properties, such as boiling point, melting point and stability. An element is the simplest form of matter and cannot be broken down further by chemical means.