Average Atomic Mass of Boron Materials At least 45 Pennies Digital balance
Procedure 1. As in the previous activity, use pennies to make one atom of boron-10 and four atoms of boron-11. Protons are the head side of pennies and neutrons are the tail side of pennies. 2. Measure the mass of the one boron-10 atom you made. Record it in the data table below. 3. Measure the total mass of all four of the boron-11 atoms you made. Record it in the data table below. 4. Calculate the average mass of one atom in your sample of boron-10. Do this by dividing the mass of boron-10 by the number of boron-10 atoms. 5. Calculate the average mass of one atom in your sample of boron-11. Do this by dividing the mass of boron-11 by the number of boron-11 atoms. 6. Calculate the proportion of your entire boron sample (all five atoms combined) that is boron-10. Boron-10 is ______ atom out of _______ total. 7. Calculate the proportion of your entire boron sample (all five atoms combined) that is boron-11. Boron-11 is ______ atoms out of ______ total. Why is the proportion of boron-11 four times greater than the proportion of boron-10? It is because there are four times as many boron-11 atoms as there are boron-10 atoms in the penny-boron sample you made. Thus, the proportion of boron-11 is four times greater. 8. Multiply the average mass of one atom of each isotope times the proportion for that isotope, and write the number in the last column. Do not round. 9. Add the two proportioned average masses together to get the total average atomic mass of penny-boron. Round this number to the nearest tenth of a gram.
Data ISOTOPE
NUMBER OF ATOMS
TOTAL MASS OF ATOMS
AVERAGE MASS OF ONE ATOM
PROPORTION OF ENTIRE SAMPLE
Boron-10
0.20
Boron-11
0.80
PROPORTION X AVERAGE MASS
Total Average Atomic Mass of Sample
50
Energy From Uranium