mass number
noun Physics.
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. Symbol: A
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What’s The Word for More Than One Software?The word software is a mass noun because it can be used to refer to a mass (or nonspecific number) of computing programs or products. Mass nouns function as both singular and plural nouns. They can describe either one item, multiple items of the same type, or an entire category of items. Some examples include bread, rice, hair, garbage, and ice. It isn’t necessary to add …
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Origin of mass number
First recorded in 1920–25
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Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for mass number
mass number
noun
the total number of neutrons and protons in the nucleus of a particular atomSymbol: A Also called: nucleon number
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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Science definitions for mass number
mass number
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. Also called nucleon number Compare atomic mass atomic weight.
The American Heritage® Science Dictionary
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