Question

The atomic mass of chlorine represents the mass of the most common naturally occurring isotope of chlorine. Is the statement true or false and why?

Answer 1

I think the correct answer would be false. The atomic mass of chlorine does not represent the mass of the most common naturally occurring isotope of chlorine. The atomic mass of any compound is the average of the atomic masses of the naturally occurring isotopes of an element. 

Answer 2

Answer: The given statement is true.

Explanation:

Average atomic mass is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

The equation used to calculate average atomic mass follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$

Chlorine element has 2 naturally occurring isotopes: Cl-35 and Cl-37

Percentage abundance of Cl-35 isotope = 75 %

Percentage abundance of Cl-37 isotope = 25 %

Average atomic mass of chlorine element = 35.45 amu

As, the average atomic mass of chlorine is closer to the mass of Cl-35 isotope. This means that the average atomic mass of an element lies closer to the isotope having high percentage abundance or teh most commonly occurring isotope.

Hence, the given statement is true.