An unknown element X has the following isotopes: ⁵²X (86.50% abundant), ⁴⁹X (8.00% abundant), ⁵⁰X (5.50% abundant). What is the average atomic mass in amu of X?

Answer 1

To solve a problem like this, we can multiply the mass of each isotope by the percentage abundance of that isotope...

52 amu X 0.8650 = 44.98 amu

49 amu X 0.0800 = 3.92 amu

50 amu X 0.0550 = 2.75 amu

Then add 44.98 amu + 3.92 amu + 2.75 amu = 51.65 amu.

The average atomic mass of element X is 51.65 amu.