A newly discovered element, X, has two naturally occurring isotopes. 87.8 percent of the sample is an isotope with a mass of 267.8 u, and 12.2 percent of the sample is an isotope with a mass of 269.9 u. What is the weighted average atomic mass for this element?

Question

Chemistry

Jenny Flowers

15 July, 17:08

A newly discovered element, X, has two naturally occurring isotopes. 87.8 percent of the sample is an isotope with a mass of 267.8 u, and 12.2 percent of the sample is an isotope with a mass of 269.9 u. What is the weighted average atomic mass for this element?

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Akira Bowers · 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.