Worksheet - Isotopes and Average Atomic masses Directions: SHOW ALL WORK! BOX IN YOUR ANSWERS 1. Four isotopes of lead include lead-204, lead-206, lead-207, and lead-208. The average atomic mass of a lead atom is 207.2 amu. Which isotope of lead is likely to be the most abundant? 2. What do all isotopes of an element have in common? 3. Explain why carbon-14 and nitrogen-14 are not considered isotopes 4. Write the atomic symbol (symbol notation) for the two isotopes of uranium(U), whose atomic number is 92. One isotope has 142 neutrons, and the other isotope has 146 neutrons. 5. Calculate the average atomic mass of the element iron(Fe) using the following data Isotope abundance 6% Iron-54 Iron-56 92% Iron-57 2% 6. Calculate the average atomic mass of the element nitrogen(N) using the following data: Isotope % abundance Nitrogen-14 Nitrogen-15 Nitrogen-16 95% 3% 2% 7. Calculate the average atomic mass of the element Iodine(I) using the following data: Isotope % abundance Iodine-125 Iodine-126 Iodine-128 90.5% 6.5% 3%