mass number

American  

noun

Physics.

1. the integer nearest in value to the atomic weight of an atom and equal to the number of nucleons in the nucleus of the atom. A

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mass number British  

noun

1. Also called: nucleon number.   A.  the total number of neutrons and protons in the nucleus of a particular atom

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mass number Scientific  

1. The total number of protons and neutrons in the nucleus of an atom. For example, nitrogen has 7 protons and 7 neutrons in its nucleus, giving it a mass number of 14. Isotopes of elements are distinguished by their mass number; for example, carbon-12 and carbon-14 have mass numbers of 12 and 14 respectively.

2. Also called nucleon number

3. Compare atomic mass atomic weight

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Etymology

Origin of mass number

First recorded in 1920–25

Compare meaning

How does mass-number compare to similar and commonly confused words? Explore the most common comparisons:

• mass number vs. atomic mass
• atomic number vs. mass number
• atomic weight vs. mass number

Example Sentences

As an example, the masses and radii of all nuclei up to mass number 50 were calculated using this method.

From Science Daily

“I remember being fixated on the fat mass number and thinking I better be leaner to be a better runner,” Bullat said.

From Seattle Times

Given the mass number of people that saw their credit scores fall, and the special circumstances that surrounded it, is it time to reconsider our credit scoring system?

From Forbes

Combined with the diameter, the mass number showed that Kepler-10c cannot be a gaseous world but must comprise very dense material.

From BBC

If you walk into Best Buy, it's rather overwhelming to look at the mass number available.

From Inc