Relative atomic mass (Ar) is the ratio of the average mass per atom of the naturally occurring form of an element to 1/12 of the mass of nuclide 12C. The term atomic weight is synonymous with the relative atomic mass.
Generalic, Eni. "Relative atomic mass." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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Periodic Table