Share this entry
mass number Syllabification: mass num·ber
Pronunciation: /ˈmas ˌnəmbər/

Definition of mass number in English:


The total number of protons and neutrons in a nucleus.
Example sentences
  • The sum of the protons and neutrons is called the mass number.
  • Various numbers are used to define nuclei: the atomic number, Z, is the number of protons, while the mass number is the sum of the atomic number and the number of neutrons, N.
  • The mass number gives you the total number of protons and neutrons in the nucleus of that element.
Definition of mass number in:
Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.

Subscribe to remove ads and access premium resources