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ANSWERS to Lesson 1.3.3 Activity Questions ( pg 60-62). 1. Use the pictures of the 10 atoms above to complete the first data table. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 6. 6. 6. 6. 5. 6. 6. 6. 6. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5.
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1. Use the pictures of the 10 atoms above to complete the first data table.
5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 5 6 6 6 6 5 5 5 5 5 5 5 5 5 5
2. How many different isotopes of boron are pictured above? Explain what they are. 2, Boron-10 and Boron-11
3. How many of each type of isotope are present in the sample of 10 atoms? 2 Boron-10, 8 Boron-11
4. What is the atomic mass of each type of isotope? How did you arrive at your answer? 10, 11 (protons + neutrons = atomic mass for each atom)
How would you figure out the average atomic mass of the ten atoms? Complete the calculation and show your work. How does your answer compare to the atomic weight of boron listed in the periodic table? (2 x 10) + (8 x 11) = 10.8 10 It’s the same as on the periodic table!
Imagine you were able to examine 100 atoms of boron. What are the mass numbers of the isotopes you expect to find? How many atoms of each isotope would you expect to find? Express your answers in %s. Boron-11, Boron-10 80 Boron-11, 20 Boron-10 80% Boron-11, 20% Boron-10
5 10.81 5 5 18 or 19 Cl 17 17 35.45 Li 3 3 3 3 or 4
50.94 23 23 27 or 28 N 7 14.01 7 7 or 8 12 or 13 12 Mg 24.31 12 12 18 18 18
9. Which isotope of argon is the most commonly found? Explain your reasoning. 22 because the average atomic mass is close to 40.
10. If you somehow managed to have a single atom of lithium isolated, how many neutrons will it probably have in its nucleus? Explain. 4, the average atomic mass is close to 7