# Worksheet3AtomsandIons1.docx

Worksheet 3: Chapter 4

1) Neon has 3 different isotopes, neon-20, neon-21, and neon-22. The first isotope has a mass of 19.992 amu and an abundance of 90.60%. The second isotope (neon-21) has an abundance of 0.21%. The third isotope has a mass of 21.991 amu and an abundance of 9.20%. What is the mass of the second isotope?

2) A certain element has the 4 isotopes. Given the following data, calculate the average atomic mass of the element and identify which element it is.

 Isotope % abundance Mass ( amu) 1 5.80% 53.9396 2 91.72% 55.9350 3 2.20% 56.9354 4 0.28% 57.9333

3) Rubidium-85 and rubidium-87 are the only two isotopes of that element. Rubidium-85 has a mass of 84.912 amu and accounts for 72.17% of all rubidium. Calculate the mass of rubidium-87.

4) Chromium has four isotopes. Chromium-50 (mass of 49.946 amu and 4.35% abundance), chromium-52 (mass of 51.941 amu and 83.79% abundance), chromium-53 (mass of 52.941 amu and 9.50% abundance), and chromium-54 (mass of 53.939 amu and 2.36% abundance). Calculate the average atomic mass of chromium.

5) Chapter 4 #’s 9-13 all, 17, 19, 20 and 42 page 85b – 85d under the Questions and Problems section.