Definition of mass number in English:

mass number

Line breaks: mass num¦ber

noun

Physics
The total number of protons and neutrons in a nucleus.
More 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.

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Word of the day hubris
Pronunciation: ˈhjuːbrɪs
noun
excessive pride or self-confidence