Question

Atomic weight of chlorine is taken as 35.43 a. m. u and not a whole number. Give reason ​

Answer 1

Answer:

The answer to why chlorine has an atomic weight of 35.43 not a whole number is because of something called isotopes.

Isotopes are atoms with the same number of protons (in the case of chlorine that means 17 protons) but different numbers of neutrons. Chlorine has two common isotopes, Chlorine-35 and Chlorine-37.

So, we take the relative atomic mass:

The RELATIVE atomic mass, is a weighted average of the masses of all the isotopes of chlorine.

Relative Atomic Mass = (75/100 x 35) + (25/100 x 37) = 35.5

Hope it helps