The mass number (symbol a, from the german word Protons and neutrons are collectively called nucleons. Atomgewicht, atomic weight), [1] also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus.
The mass number of an atom or isotope of an element is defined as the sum of the total number of protons and neutrons in its nucleus The sum of the number of protons and neutrons present in its nucleus is called mass number of an atom of an element In contrast, relative atomic mass is the average of atomic masses of all the isotopes of an element with their abundance compared to carbon 12.
It can be calculated by adding the number of neutrons and the number of protons (atomic number) together. Mass number is the sum of the number of protons and neutrons in an atom In other words, it is the number of nucleons in an atom Mass number is also a whole number, with the symbol a in general notation
It is given on the upper right or upper left side of an element symbol.
