Atomic Mass Unit

The atomic mass unit, also called the dalton after the chemist John Dalton, is a small unit of mass used to express atomic masses and molecular masses. It is defined to be 1/12 of the mass of one atom of Carbon-12. The abbreviations "u", "amu" and "Da" are used for this unit; often, atomic masses are written without any unit and then the amu is implied.

The value is

1 amu ≈ 1.6605387 × 10^-27 kilograms.

See 1 E-27 kg for a list of objects which have a mass of about 1 amu.

The unit is convenient because one hydrogen atom weighs approximately 1 amu, and more generally an atom or molecule that contains n protons and neutrons will have a mass approximately equal to n amu. This is only a rough approximation however, since it doesn't account for the mass contained in the binding energy of the nucleus.

Another reason the unit is used is that it is much easier to compare masses of atoms and molecules (determine relative masses) than to measure their absolute masses. Finding the mass of a given molecule in amus is thus easier than to express 1 amu in terms of kilograms.

Avogadro's number N_A and the mole are defined so that one mole of a substance with atomic or molecular mass 1 amu will weigh precisely 1 gram. As an equation:

1 amu = 1 gram/mole

or equivalently

1 gram = N_A amu

For example, the molecular mass of water is 18.01508 amu, and this means that one mole of water weighs 18.01508 grams, or conversely that 1 gram of water contains N_A/18.01508 ≈ 3.3428 × 10²² molecules.

Frequency of Internet Keywords: Atomic Mass Unit

Modern Translation: Atomic Mass Unit

Language		Translations for "atomic mass unit"; alternative meanings/domain in parentheses.
Danish		atomvægt, atomar masseenhed, masseenhed. (various references)

Dutch		atoommassa-eenheid, atomaire massa-eenheid, atomaire massaeenheid, ame, massa-eenheid, eenheid van atoommassa. (various references)

Finnish		atomimassayksikkö. (various references)

French		unité de masse atomique, unité de masse. (various references)

German		atomare Masseneinheit, atomare Masseeinheit. (various references)

Greek		u (E or emf, electromotive force, potential difference, tension), μονάδα μάζας, μονάδα ατομικής μάζας. (various references)

Italian		unit� di massa atomica. (various references)

Pig Latin		atomicay assmay itunay

Portuguese		unidade de massa atomica. (various references)

Russian		атомная единица массы (amu atomic mass unit). (various references)

Spanish		unidad de masa atómica, unidad de masa. (various references)

Swedish		atommassenhet, atomär massenhet, universell atommassenhet. (various references)
Source: compiled by the editor from various translation references.

Anagrams: Atomic Mass Unit

Scrabble® Enable2K-Verified Anagrams
	Words within the letters "a-a-c-i-i-m-m-n-o-s-s-t-t-u"
	-2 letters: mastications.
	-3 letters: automatisms, mastication, monasticism, numismatics, numismatist.
	-4 letters: actuations, anatomists, automatics, automatism, catamounts, causations, communists, numismatic, satiations, situations, summations.
	-5 letters: aconitums, actinisms, actiniums, actuation, ammoniacs, ammonitic, anatomist, antiatoms, atomistic, atticisms, autistics, automatic, catamount, causation, citations, communist, iotacisms, isostatic, mainmasts, manicotti, miasmatic, miscounts, monastics, mosaicism, mosaicist, musicians, mutations, satiation, simoniacs, situation, stictions, summation, titanisms, titaniums.
Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro.

Domain	Definition
Aerospace	See atomic mass, note.Abbreviation amu. (references)
Electrical Engineering	The mass of an atom of carbon 12C divided by 12. Source: European Union. (references)
Source: compiled by the editor from various references; see credits.

Expression	Frequency per Day
atomic mass unit	11
Source: compiled by the editor from various references; see credits.

Atomic Mass Unit

Definition: Atomic Mass Unit

Atomic Mass Unit

Noun

Specialty Definition: Atomic Mass Unit

Aerospace

Electrical Engineering

Specialty Definition: Atomic mass unit

Frequency of Internet Keywords: Atomic Mass Unit

atomic mass unit

Modern Translation: Atomic Mass Unit

Danish

Dutch

Finnish

French

German

Greek

Italian

Pig Latin

Portuguese

Russian

Spanish

Swedish

Anagrams: Atomic Mass Unit

Scrabble® Enable2K-Verified Anagrams

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