Relative atomic mass (symbol: Ar) is a dimensionless physical quantity, the ratio of the average mass of atoms of an element (from a given source) to 1/12 of the mass of an atom of carbon-12 (known as the unified atomic mass unit). The term is usually used, without further qualification, to refer to the standard atomic weights published at regular intervals by the International Union of Pure and Applied Chemistry (IUPAC) and which are intended to be applicable to normal laboratory materials. These standard atomic weights are reprinted in a wide variety of textbooks, commercial catalogues, wallcharts etc., and in the table below.
The term "atomic weight" (of the element) is also used to describe this physical quantity, and is synonymous with it. However, its continued use has attracted considerable controversy since at least the 1960s (see below).
Read more about Relative Atomic Mass: Definition, Naming Controversy, Determination of Atomic Weight, Periodic Table With Atomic Weights
Famous quotes containing the words relative, atomic and/or mass:
“She went in there to muse on being rid
Of relative beneath the coffin lid.
No one was by. She stuck her tongue out; slid.”
—Gwendolyn Brooks (b. 1917)
“Other centuries had their driving forces. What will ours have been when men look far back to it one day? Maybe it won’t be the American Century, after all. Or the Russian Century or the Atomic Century. Wouldn’t it be wonderful, Phil, if it turned out to be everybody’s century, when people all over the world—free people—found a way to live together? I’d like to be around to see some of that, even the beginning.”
—Moss Hart (1904–1961)
“No atomic physicist has to worry, people will always want to kill other people on a mass scale. Sure, he’s got the fridge full of sausages and spring water.”
—William Burroughs (b. 1914)