0 the mass of an atom of a particular chemical element, usually expressed in atomic mass units -- 相對原子質量，原子量（某種特定化學元素一個原子的質量，通常以原子質量單位表示）
For the natural isotopic composition of each element it shows "name", "atomic number", "symbol", "atomic weight" (or relative atomic mass) and a link to the element's "isotopes".
It is numerically equal to the relative atomic mass (or atomic weight) in grams.
However, atomic weight, ie, relative atomic mass, is a dimensionless quantity, and can not take the units of grams per mole.
Si, which has a relative atomic mass of.
Its isotopic composition would be measured with a mass spectrometer to determine its average relative atomic mass.
The term "atomic weight" is being phased out slowly and being replaced by "relative atomic mass", in most current usage.
The relative atomic mass (a weighted average) of these isotopes is the atomic weight listed for the element in the periodic table.
It is fixed by the definitions of the mole and of relative atomic mass.
