Jisim atom relatif

Jisim atom relatif (simbol: A_r) ialah satu kuantiti fizikal tanpa dimensi, iaitu nisbah jisim purata atom-atom satu unsur (daripada satu sumber tertentu) kepada 1/12 daripada jisim atom karbon-12 (dikenali sebagai unit jisim atom bersatu).^[1]^[2] Istilah ini biasanya digunakan untuk merujuk kepada berat atom piawai yang diterbitkan dalam selang yang tetap oleh IUPAC^[3]^[4] dan bertujuan untuk boleh digunakan pada bahan-bahan makmal biasa. Berat-berat atom piawai ini dicetak semula dalam pelbagai buku teks, katalog komersial, carta dinding, dll., dan juga di dalam jadual di bawah.

Istilah "berat atom" (sesuatu unsur) juga digunakan untuk menyatakan kuantiti fizikal ini, dan ia bersinonim dengan istilah di atas. Namun, penggunaannya yang berterusan telah menyebabkan kontroversi sejak tahun 1960-an.^[5]

Rujukan sunting

^ International Union of Pure and Applied Chemistry (1980). "Atomic Weights of the Elements 1979" (PDF). Pure Appl. Chem. 52 (10): 2349–84. doi:10.1351/pac198052102349.
^ Templat:GreenBookRef2nd
^ The latest edition is International Union of Pure and Applied Chemistry (2006). "Atomic Weights of the Elements 2005" (PDF). Pure Appl. Chem. 78 (11): 2051–66. doi:10.1351/pac200678112051.
^ The updated list of standard atomic weights is expected to be formally published in late 2008. The IUPAC(International Union Of Pure And Applied Chemistry) Commission on Isotopic Abundances and Atomic Weights announced Diarkibkan 2009-02-04 di Wayback Machine in August 2007 that the standard atomic weights of the following elements would be revised (new figures quoted here): lutetium 174.9668(1); molybdenum 95.96(2); nickel 58.6934(4); ytterbium 173.054(5); zinc 65.38(2). The recommended value for the isotope amount ratio of ⁴⁰Ar/³⁶Ar (which could be useful as a control measurement in argon–argon dating) was also changed from 296.03(53) to 298.56(31).
^ de Bièvre, P.; Peiser, H. S. (1992). "'Atomic Weight'—The Name, Its History, Definition, and Units" (PDF). Pure Appl. Chem. 64 (10): 1535–43. doi:10.1351/pac199264101535.

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[IUPAC1979-1] International Union of Pure and Applied Chemistry (1980). "Atomic Weights of the Elements 1979" (PDF). Pure Appl. Chem. 52 (10): 2349–84. doi:10.1351/pac198052102349.

[GreenBook-2] Templat:GreenBookRef2nd

[3] The latest edition is International Union of Pure and Applied Chemistry (2006). "Atomic Weights of the Elements 2005" (PDF). Pure Appl. Chem. 78 (11): 2051–66. doi:10.1351/pac200678112051.

[4] The updated list of standard atomic weights is expected to be formally published in late 2008. The IUPAC(International Union Of Pure And Applied Chemistry) Commission on Isotopic Abundances and Atomic Weights announced Diarkibkan 2009-02-04 di Wayback Machine in August 2007 that the standard atomic weights of the following elements would be revised (new figures quoted here): lutetium 174.9668(1); molybdenum 95.96(2); nickel 58.6934(4); ytterbium 173.054(5); zinc 65.38(2). The recommended value for the isotope amount ratio of ⁴⁰Ar/³⁶Ar (which could be useful as a control measurement in argon–argon dating) was also changed from 296.03(53) to 298.56(31).

[IUPAChist-5] Bièvre, P.; Peiser, H. S. (1992). "'Atomic Weight'—The Name, Its History, Definition, and Units" (PDF). Pure Appl. Chem. 64 (10): 1535–43. doi:10.1351/pac199264101535.

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