Calcium has three different isotopes. One has a mass of 35.00 amu; another has a mass of 41.00 amu; the third has a mass of 40.00 amu. Which isotope is most abundant of the three? How do you know?

Question

I want to say it is the isotope with the largest atomic mass unit, but there are no percentages so I don't know of a way to be sure which one could be more abundant.

Answer 1

Hi Sam

Since you are not given any percentages you need to look on the periodic table. When you look up the atomic mass for calcium you will see that it is 40.078 amu. Remember, this atomic mass is the average of all the isotopes of calcium. Since Ca-40 is closest to the average of 40.078 then it is the most abundant.

Hope that helps!