atomic mass unit


nounPhysics.
  1. Also called dalton . a unit of mass, equal to 1/12 (0.0833) the mass of the carbon-12 atom and used to express the mass of atomic and subatomic particles.

  2. (formerly) a unit of mass, equal to 1/16 (0.0625) the mass of an oxygen atom having atomic mass 16.Abbreviations: amu, AMU

Origin of atomic mass unit

1
First recorded in 1950–55

Words Nearby atomic mass unit

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British Dictionary definitions for atomic mass unit

atomic mass unit

noun
  1. a unit of mass used to express atomic and molecular weights that is equal to one twelfth of the mass of an atom of carbon-12. It is equivalent to 1.66 × 10 –27 kg: Abbreviation: amu Also called: unified atomic mass unit, dalton

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

Scientific definitions for atomic mass unit

atomic mass unit

  1. A unit of mass equal to 112 the mass of an atom of the most common isotope of carbon (carbon 12), which is assigned a mass of 12 and has a value of 1.660 X 10-24 grams. A hydrogen atom has a mass of 1 atomic mass unit since its mass is 112 the mass of carbon 12. Also called dalton

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