Isotopy

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:  ${}_8{}^{16}O \mathrm{and} {}_8{}^{17}\mathrm{O}$

Example:

If the percentage abundance of chlorine is 25% of  ${}_{17}{}^{37}CL$ and the remaining Percentage is  ${}_{17}{}^{35}\mathrm{CL}$.

Calculate the relative atomic mass of chlorine.

Solution:

25% of ${}_{17}{}^{37}CL$ and the remaining percentage

= 100 – 25 = 75% of  ${}_{17}{}^{35}CL$

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.