The element loncapium has three isotopes. the first lc-82 has a mass of 81.2372 amu and makes up 47.36% of a standard sample. the second isotope, lc-83, has a mass of 82.5759 amu and makes up 38% of a standard sample. the third isotope, lc-85 has a mass of 84.0536 amu and makes up the remainder of the sample. what is the average atomic mass of this element?

The average atomic mass of lonacapium 82.1581 amu.

Solution: To calculate average atomic mass of element, we use the formula:

     ....(1)

First isotope, Lc-82

Atomic Mass of Lc-82 isotope=81.2372 amu

Percentage abundance = 47.36%= 0.4736

Second isotope, Lc-83

Atomic Mass of Lc-83 isotope=82.5759 amu

Percentage abundance = 38%= 0.3800

Third isotope, Lc-85

Atomic Mass of Lc-85 isotope =84.0536 amu

Percentage abundance = 100% - 47.36% -38% = 14.64%= 0.1464

Putting the values in equation 1.

Average atomic mass of Loncapium = 82.1581 amu