Question

4. An element has two naturally occurring isotopes. The mass numbers of these isotopes are 111 amu and 113 amu, with natural abundances of 25% and 75%, respectively. Calculate the atomic mass for this element. 6 pts

Answer 1

The atomic mass is calculated by the formula shown below.

Atomic mass = (mass1* abundance1) + (mass2* abundance2)

Given that,

mass1= 111 amu

abundance1 = 25 % = 0.25

mass2 = 113 amu

abundance2 = 75% = 0.75.

So

Atomic mass = (111 * 0.25) + ( 113 * 0.75) = 112.5 amu

So the atomic mass of the element is 112.5 amu.