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The mass of an atom or a molecule is referred to as the atomic mass. The atomic mass is used to find the average mass of elements and molecules and to solve stoichiometry problems.
The name "atomic mass" is used for historical reasons, and originates from the fact that chemistry was the first science to investigate the same physical objects on macroscopic and microscopic levels. In addition, the situation is rendered more complicated by the isotopic distribution. On the macroscopic level, most mass measurements of pure substances refer to a mixture of isotopes. This means that from a physical stand point, these mixtures are not pure. For example, the macroscopic mass of oxygen (O2) does not correspond to the microscopic mass of O2. The former usually implies a certain isotopic distribution, whereas the latter usually refers to the most common isotope (16O2). Note that the former is now often referred to as the "molecular weight" or "atomic weight
Used by Template:Molar mass
{{Atomic mass|Fe}} = 55.845
{{Atomic mass|0}} = 0