Question

An atom has the following three isotopes: 24 amu (percent abundance = 78.99%)25 amu (percent abundance =10.00\%) , and 26 amu (percent bundance=11.01\%) . Calculate the average atomic mass. What is the identity of this atom based on your calculation?

Answer 1

We multiply each mass with its percentage.
24*(78.99/100) = 18.96
25*(10/100)= 2.5
26*(11.01/100)= 2.86
Then add these together.
18.96+2.5+2.86= 24.32amu
An element that has an average mass of nearly 24.32amu would be Mg (magnesium)

Answer 2

The average atomic mass is 24.31. The element is likely Magnesium.

Work:
24(0.7899) = 18.95
25(0.1000) = 2.5
26(0.1101) = 2.86
18.95 + 2.5 + 2.86 = 24.31