A certain element consists of two stable isotopes.The first has a mass of 14.0031 amu and a percent natural abundance of 99.63%.The second has a mass of 15.001 amu and a percent natural abundance of 0.37%.What is the atomic weight of the element?

Question

Quizplus · Accepted Answer

The atomic weight can be calculated using the formula:

Atomic weight = (mass of isotope 1 x % abundance of isotope 1) + (mass of isotope 2 x % abundance of isotope 2) / 100

Substituting the values given in the question:

Atomic weight = (14.0031 amu x 99.63%) + (15.001 amu x 0.37%) / 100
Atomic weight = (13.9491 amu) + (0.05554 amu) 
Atomic weight = 14.0046 amu

Rounding off to two decimal places, the atomic weight of the element is 14.01 u, which is option C.

A Certain Element Consists of Two Stable Isotopes