Question

A newly discovered element, X, has two naturally occurring isotopes. 93.5 percent of the sample is an isotope with a mass of 268.9 u, and 6.5 percent of the sample is an isotope with a mass of 269.9 u. What is the weighted average atomic mass for this element?. . 268.5 u . . 269.0 u . . 269.4 u . . 269.8 u.

Answer 1

The weighted average atomic mass (m) of the newly discovered element X is the sum of the products of its isotopes percentage and mass.

                    m = (0.935) x (268.9 u) + (0.065) x (269.9 u) = 268.965 u

Thus, the weight of the atom is approximately 269.0 u.

Answer 2

To calculate the average mass of the element, we take the summation of the product of the isotope and the percent abundance. In this case, it is 0.935 * 268.9 amu + 0.065* 269.9 amu. This is equal to an average mass of 268.965 amu.