The sum of the number of neutrons and protons in an atomic nucleus.

The total number of protons and neutrons in an atom; the mass number A.

(See mass number) - The nucleon number of an atom is the number of neutrons in the nucleus of an atom. Each element can have several different nucleon numbers. Each one corresponds to a different isotope of the element.

A synonym for mass number.

The number of nucleons (total number of protons and neutrons) in a nucleus. Radioactivity