A mystery element’s mass spectrum shows it to be 13.92 % Isotope A (219 amu), 72.16 % Isotope B (222 amu), and 13.92 % Isotope C (225 amu).
a. What is the atomic weight of the element?

b. What is the element?

The given element is Radon because its atomic weight is 222 amu.

Explanation:

Given data:

Percentage of A-219 = 13.92%

Percentage of B-222 = 72.16%

Percentage of C-225 = 13.92%

Atomic weight of element = ?

Solution:

Average atomic mass = (abundance of A isotope × its atomic mass) +(abundance of B isotope × its atomic mass) + (abundance of C isotope × its atomic mass)  / 100

Average atomic mass  = (13.92×219)+(72.16×222) + (13.92×225)/100

Average atomic mass =  3048.48 + 16019.52 +3132/ 100

Average atomic mass  = 22200 / 100

Average atomic mass  = 222 amu.

The given element is Radon because its atomic weight is 222 amu.