A new element is found that has an isotope that occurs naturally in 75% abundance and has a mass oF₄8.0 u and another isotope that occurs naturally in 25% abundance with a mass of 50.0 u. What is the atomic mass of the element?

Question

Quizplus · Accepted Answer

To find the atomic mass, we need to calculate the weighted average of the masses of both isotopes. We can use the following formula:
Atomic mass = (% abundance of isotope 1 x mass of isotope 1) + (% abundance of isotope 2 x mass of isotope 2)
Plugging in the given values, we get:
Atomic mass = (0.75 x 108.0 u) + (0.25 x 50.0 u) 
Atomic mass = 81.0 u + 12.5 u 
Atomic mass = 93.5 u
Therefore, the best answer choice is B) 48.5 u.

A New Element Is Found That Has an Isotope That