Mass Number | Definition, Use, Properties, Examples

what is mass number

Definition of Mass Number The mass number (symbol A, from the German word Atomgewicht [atomic weight]), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is approximately equal to the atom’s atomic (also known as isotopic) mass expressed in … Read more

Atomic Number | Discovery, Formula, History, Properties

atomic number

Definitions of Atomic Number In the symbol representing a particular nuclear or atomic species, the atomic number may be indicated as a left subscript. Atoms of each element contain a characteristic number of protons. In fact, the number of protons determines what atom we are looking at (e.g., all atoms with six protons are carbon … Read more