Questions: A fictitious element, Fi, consists of three isotopes: Fi-16, Fi-17, and Fi-19. The notation Fi-16, Fi-17, and Fi-19 indicates that all three are atoms of Fi, each with the same number of protons, yet they have different masses because they have different numbers of neutrons. The masses of these isotopes, in units of atomic mass units (amu), and their percent abundances are listed below. Fi-16: 11.22%, 16.11 amu Fi-17: 18.43%, 17.04 amu Fi-19: 70.35%, 19.13 amu Based on this information, calculate the average atomic mass of Fi.

Solution Steps

To calculate the average atomic mass, we first need to convert the percent abundances of each isotope to decimal form by dividing each percentage by 100.

\[ \text{Abundance of Fi-16} = \frac{11.22}{100} = 0.1122 \] \[ \text{Abundance of Fi-17} = \frac{18.43}{100} = 0.1843 \] \[ \text{Abundance of Fi-19} = \frac{70.35}{100} = 0.7035 \]

Next, we multiply the mass of each isotope by its corresponding decimal abundance.

\[ \text{Contribution of Fi-16} = 16.11 \, \text{amu} \times 0.1122 = 1.8075 \, \text{amu} \] \[ \text{Contribution of Fi-17} = 17.04 \, \text{amu} \times 0.1843 = 3.1417 \, \text{amu} \] \[ \text{Contribution of Fi-19} = 19.13 \, \text{amu} \times 0.7035 = 13.4576 \, \text{amu} \]

Finally, we sum the contributions of each isotope to find the average atomic mass of Fi.

\[ \text{Average Atomic Mass} = 1.8075 \, \text{amu} + 3.1417 \, \text{amu} + 13.4576 \, \text{amu} = 18.4068 \, \text{amu} \]

Final Answer