Relative atomic mass Ar:
The realtive atomic mass of an element compares the mass of atoms of that element with an atom of 12,6 C isotope which is given a mass of exactly 12 units. It is the average value of the mass of an atom of the element, taking into account the different proportions in which the isotopes occur.
Relative formula mass or realtive molecular mass, Mr.
Relative formula masses are used for…