Learn all you should know about the Atomic Theory, an important topic in chemistry.
Having the percentage abundance of the isotopes for a particular element, one could find the relative atomic mass (r.a.m.) for that element.
For example, to find the relative atomic mass (r.a.m.) chlorine.
One atom of 35Cl has a mass of 35 One atom of 37Cl has a mass of 37 17 17
So 75 atoms of 35Cl have ? mass So 25 atoms of 37Cl have ? mass
35 X 75 = 2625 37 X 25 = 925
So 100 atom of the two types of isotopes together have the mass of 2625 + 925 = 3550
So the relative atomic mass (r.a.m.) of chlorine is: 3550 = 35.5