DEFINITIONS

mass number

SEE SYNONYMS FOR mass number ON THESAURUS.COM

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

Content related to mass number

Why Veterans Day And The Number 11 Are Tied TogetherNovember 11th is the 315th day of the year (except on leap years). It’s also Veterans Day, a federal holiday honoring all military veterans.
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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.
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Words nearby mass number

mass medium, mass meeting, mass merchandiser, mass movement, mass noun, mass number, mass observation, mass peristalsis, mass production, mass psychogenic illness, mass psychology

Origin of mass number

First recorded in 1920–25
Dictionary.com Unabridged 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 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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 Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.