definitions

atomic mass

SEE MORE SYNONYMS FOR atomic mass ON THESAURUS.COM

noun Chemistry.

the mass of an isotope of an element measured in units formerly based on the mass of one hydrogen atom taken as a unit or on 1/16 (0.0625) the mass of one oxygen atom, but after 1961 based on 1/12 (0.0833) the mass of the carbon-12 atom. Abbreviation: at. m.

RELATED CONTENT

Tick, Tock: What Is The “Doomsday Clock?”What is the Doomsday Clock? Doomsday  is one of those evocative words that paint a very vivid picture. As our definition states, “the day of the Last Judgment, at the end of the world; nuclear destruction of the world; given to or marked by forebodings or predictions of impending calamity; especially concerned with or predicting future universal destruction.” As you can see, it’s about as …
READ MORE
How Are Newly Discovered Chemical Elements Named?Unlike common elements, newer elements are synthesized in a lab; they are not observed in nature. They are very unstable and quickly dissolve into other elements. So how do scientists name them?
READ MORE

Nearby words

atomic energy authority, atomic energy commission, atomic force microscope, atomic heat, atomic hydrogen, atomic mass, atomic mass unit, atomic number, atomic orbital, atomic pile, atomic power

Origin of atomic mass

First recorded in 1895–1900
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for atomic mass

atomic mass

noun chem

the mass of an isotope of an element in atomic mass units
short for relative atomic mass See atomic weight
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

Medicine definitions for atomic mass

atomic mass

n.

The mass of an atom, usually expressed in atomic mass units.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for atomic mass

atomic mass

The mass of a given atom or molecule, expressed in atomic mass units. Compare atomic weight. See also mass number.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.