A term used to represent the mean relative atomic mass of an element in nature, as distinct from the relative atomic mass of a single isotope.
Former term for the more specific relative atomic mass.
The ratio of the average mass per atom of the naturally occurring form of an element to 1/12 of the mass of a carbon-12 atom. Symbol Aᵣ; abbreviation RAM or r.a.m. For elements with several isotopes, the most stable isotope is treated as the representative.