Question

Why is atomic mass is also called relative atomic mass?

Answer 1

Relative atomic mass. A relative atomic mass (also called atomic weight; symbol: Ar) is a measure of how heavy atoms are. It is the ratio of the average mass peratom of an element from a given sample to 1/12 the mass of acarbon-12 atom. ... An atom of an element with a certain number of neutrons is called an isotope.