Isotope is a phenomenon in which atoms of an element possess the same atomic number but different mesa number due to differences in the number of neutrons.

Eg:  O816  and  O817


If the percentage abundance of chlorine is 25% of  CL1737 and the remaining Percentage is  CL1735.

Calculate the relative atomic mass of chlorine.


25% of CL1737 and the remaining percentage

= 100 – 25 = 75% of  CL1735


So, Mass of CL = (25/100 x 37 + 75/100 x 35)

= (0.25 x 37) + (0.75 x 35)

The relative atomic mass = 35.5.

Note: It is Isotope that makes relative atomic masses of elements to have decimal points in them. An atom, which exhibits Isotopy, is termed lsotope.

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