Question

(b) The ratio of isotopes of

and

in natural chlorine is 1:3. Calculate the

fractional atomic mass of chlorine.​

Answer 1

The atomic weight of an element is therefore the sum of the (mass x fractional abundance) of the naturally occuring isotopes. The fractional abundance is 1/100 of the percent abundance. For chlorine, AW = (34.969 x 0.7553) + (36.966 x 0.2447) amu = 35.458 amu