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ATOMIC MASS UNIT UNIFIED [1 record]
Record 1 - internal organization data 2012-02-13
Record 1, English
Record 1, Subject field(s)
- Metrology and Units of Measure
- Atomic Physics
- Chemistry
- Biotechnology
Record 1, Main entry term, English
- atomic weight unit
1, record 1, English, atomic%20weight%20unit
correct
Record 1, Abbreviations, English
- awu 2, record 1, English, awu
correct
Record 1, Synonyms, English
- atomic mass unit 3, record 1, English, atomic%20mass%20unit
correct, see observation
- amu 4, record 1, English, amu
correct
- a.m.u. 5, record 1, English, a%2Em%2Eu%2E
correct
- amu 4, record 1, English, amu
- dalton 6, record 1, English, dalton
see observation
Record 1, Textual support, English
Record number: 1, Textual support number: 1 DEF
"atomic mass unit": An arbitrarily defined unit in terms of which the masses of individual atoms are expressed: the standard is the unit of mass equal to 1/12 the mass of the carbon atom, having as nucleus the isotope with mass number 12. 7, record 1, English, - atomic%20weight%20unit
Record number: 1, Textual support number: 2 DEF
"atomic mass unit": For an element, it is the number which specifies how many times heavier one atom of the element is than one atom of hydrogen. The atomic mass unit is the unit of measure of the mass particle (atom, molecule, ion, etc.). The numerical value of the mass of a particle in amu,s is identical with the older atomic weight. The symbol is mu = 1 u and in vaccuum technology the value of this constant is 1.66056 X 10-27kg. 8, record 1, English, - atomic%20weight%20unit
Record number: 1, Textual support number: 1 CONT
The nucleus of an atom is made up of neutrons and protons. The total mass of the neutrons and protons along with the electrons gives the mass of the atom. ... Because this value is so small, a new unit of weight, the atomic weight unit (awu), is often used to express the weights of atoms. It is defined as 1/12 the weight of carbon atoms. 2, record 1, English, - atomic%20weight%20unit
Record number: 1, Textual support number: 1 OBS
Prior to Sept. 8, 1960, natural oxygen, a mixture of isotopes, served as the standard of reference with an assigned atomic weight of 16.0000 exactly. 2, record 1, English, - atomic%20weight%20unit
Record number: 1, Textual support number: 2 OBS
Historically the term "atomic weight unit" was the chemists' standard of reference for atomic weight and it was based on the weight of natural oxygen. "Atomic mass unit" was the term preferred by physicists and it was based on the oxygen-16 isotope. (See FREMA, 1960, p. 58 and MHECH, 1983, p. 171). 9, record 1, English, - atomic%20weight%20unit
Record number: 1, Textual support number: 3 OBS
The term "dalton", which is defined as 1/16th the mass of oxygen-16, is rarely used nowadays in referring to atomic mass unit because oxygen no longer serves as standard of reference. 9, record 1, English, - atomic%20weight%20unit
Record 1, Key term(s)
- atomic mass unit unified
Record 1, French
Record 1, Domaine(s)
- Unités de mesure et métrologie
- Physique atomique
- Chimie
- Biotechnologie
Record 1, Main entry term, French
- unité de masse atomique
1, record 1, French, unit%C3%A9%20de%20masse%20atomique
correct, feminine noun
Record 1, Abbreviations, French
- u.m.a. 2, record 1, French, u%2Em%2Ea%2E
feminine noun
- U.M.A. 2, record 1, French, U%2EM%2EA%2E
feminine noun
Record 1, Synonyms, French
- unité de poids atomique 3, record 1, French, unit%C3%A9%20de%20poids%20atomique
feminine noun
Record 1, Textual support, French
Record number: 1, Textual support number: 1 CONT
En accord avec les recommandations de la Commission des poids atomiques, on appelle poids atomique d'un élément (ou coefficient atomique) le poids moyen relatif des atomes d'un élément en unité de masse atomique, cette unité étant le douzième de la masse de l'isotope 12 [indice]C; cette Commission a recommandé d'utiliser la désignation poids atomique pour les éléments qui sont, pour la plupart d'entre eux à l'état naturel, des mélanges de nuclides et de réserver celle de masse atomique pour les nuclides isolés. 4, record 1, French, - unit%C3%A9%20de%20masse%20atomique
Record number: 1, Textual support number: 1 OBS
L'établissement de tables de poids atomiques [...]. [...] J. Stas [...] choisit, en 1850, comme unité de référence la seizième partie du poids atomique de l'oxygène. À partir de 1920, les physiciens prirent comme étalon la masse de l'isotope 160, à laquelle ils attribuèrent la valeur 16,000 00 g tandis que les chimistes continuaient à prendre la valeur 16,000 00 pour le poids atomique de l'oxygène naturel [...]. Mais, les deux échelles ne concordaient pas exactement et la valeur numérique du poids atomique était plus petite dans l'échelle chimique [atomic weight unit] que dans l'échelle physique [atomic mass unit], ce qui entraînait des confusions. [...] on décida [...] que l'échelle chimique basée sur la valeur 16,000 00 pour l'oxygène naturel devait être abandonnée. En 1961, les Unions internationales de physique pure et appliquée et de chimie pure et appliquée prirent la décision de recommander une modification de l'échelle des poids atomiques et d'attribuer un poids atomique de 12 à l'isotope du carbone 12 [indice]C, ce qui nécessitait de recalculer les tables de poids atomiques sur la base de 12 [indice]C =12. 4, record 1, French, - unit%C3%A9%20de%20masse%20atomique
Record 1, Key term(s)
- unité de masse atomique unifiée
Record 1, Spanish
Record 1, Campo(s) temático(s)
- Metrología y unidades de medida
- Física atómica
- Química
- Biotecnología
Record 1, Main entry term, Spanish
- unidad de masa atómica
1, record 1, Spanish, unidad%20de%20masa%20at%C3%B3mica
correct, feminine noun
Record 1, Abbreviations, Spanish
Record 1, Synonyms, Spanish
- unidad másica 3, record 1, Spanish, unidad%20m%C3%A1sica
feminine noun
- unidad de peso atómico 4, record 1, Spanish, unidad%20de%20peso%20at%C3%B3mico
feminine noun
Record 1, Textual support, Spanish
Record number: 1, Textual support number: 1 DEF
"unidad másica": Dozava parte de la masa del átomo de carbono-12. Sinónimo: "unidad de masa atómica". 3, record 1, Spanish, - unidad%20de%20masa%20at%C3%B3mica
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