Question

An element has two naturally occurring isotopes. One has an atomic mass of 247 amu with 5% abundance. The other has an atomic mass of 258 amu with 95% abundance. What is the average atomic mass of the element?

Answer 1

The average atomic mass of an element with multiple isotopes is 257.45 amu.

Step-by-step explanation:

To calculate the average atomic mass of an element with multiple naturally occurring isotopes, you need to consider the abundance and atomic mass of each isotope. In this case, the element has two isotopes: one with an atomic mass of 247 amu and 5% abundance, and the other with an atomic mass of 258 amu and 95% abundance.

Convert the percentages of abundances to decimal fractions. For the isotope with 5% abundance, it becomes 0.05, and for the isotope with 95% abundance, it becomes 0.95.

• Multiply each isotope's mass by its corresponding abundance fraction.
• Add the products from step 2 together to get the average atomic mass.
• Calculating the average atomic mass:

(247 amu x 0.05) + (258 amu x 0.95) = 12.35 amu + 245.1 amu = 257.45 amu

Therefore, the average atomic mass of the element is 257.45 amu.