1. Lab 9 The Atomic Mass of “Boltium” Purpose Calculate the atomic mass of “Boltium” Background The atomic mass of any element is a weighted average of all the naturally occurring isotopes of the element. Date:

2. Take copper for example… Take any sample of pure copper and run it through a mass spectrometer…

3. No matter where the copper came from, it will separate into the following isotopes: Copper-63; 62.939598 amu: 69.17% Copper-65; 64.927793 amu: 30.83% 62.939598 x 0.6917 + 64.927793 x 0.3083 = 63.55 (rounded) The atomic mass is calculated as a weighted average…

4. Experiment Boltium has 4 known isotopes. You will be given a sample of pure boltium. Isotope Number of Each Isotope Present in Sample Total Mass (g) Average Mass (g) % Abundance 1 2 3 4 Calculate in Analysis section

5. Analysis 1.Calculate the average mass of each isotope, record this in the data table. (Show your work here) 1.Calculate the percent abundance of each isotope, record this in the data table. (Show your work here) 1.Calculate the atomic mass of “Boltium.” This is a weighted average that factors in the abundance and mass of each isotopes of the element. (Show your work here) Results: This should be a statement that explains what a weighted average is and how it is related to atomic masses of atoms.

6. Questions 1.Why should atomic masses be calculated as a weighted average of all the naturally occurring isotopes? 2. The atomic mass of carbon is 12.011 amu. Does any isotope of carbon actually weigh this amount? Explain. 3. What did each bolt represent in this activity? 4. If you were to grab a bolt out of the sample of Boltium, what would the mass of the bolt be, on average? 5. This activity is an analogy that shows how the atomic mass of an elements is calculated. Explain two flaws of this analogy.