Beanium Activity
Name: _______________________
Objectives:
 Determine the average weights of each isotope of the fictitious element Beanium.
 Determine the relative abundances of isotopes of Beanium.
 Using experimental data, calculate the atomic mass of Beanium.
Materials:
 One sample of Beanium
 Balance
Procedure:
Part A: From the individual beakers:
1. Count out 50 beans and record the mass _____________
2. Count out 50 peas and record the mass _____________
3. Count out 50 kernels of corn and record the mass.
_____________
4. For each of the isotopes, calculate the average mass for a single isotope and record. _____________
Part B:
5. Mass the empty cup.
6. Fill the cup with Beanium from the bag at the front of the room.
7. Separate the beans, peas, and corn into three samples.
8. Mass the beans, peas, and corn individually.
9. Count the beans, peas, and corn individually.
Calculations: Place all answers below.
1. Calculate the mass of a single atom of each isotope. (hint: divide the mass by the number of atoms counted)
2. Calculate the total number of atoms present for each isotope in the Beanium sample.
3. Calculate the percent abundance of each isotope.
4. Calculate the relative atomic mass of each of the isotopes.
5. Calculate the average atomic mass of the elements of Beanium.
Total number of
atoms
Mass
Beans
Peas
Corn
Average Atomic Mass of Beanium: ___________________________
% Abundance
Relative Atomic
Mass
Questions for Analysis: Use complete sentences where applicable. If calculations are required, show all
work and box your answer.
1. Explain the difference between percent abundance and relative abundance.
2. Based on the procedure you followed, what are some possible sources of error that may affect your results?
3. In a regular element, what are the two differences and two similarities between isotopes?
4. Compare the average atomic mass you calculated to the masses of each of the isotopes, does your average
atomic mass make sense? Explain why or why not.
5. Based on your data and calculations, explain why the atomic mass of an element is a weighted average
based on relative abundance instead of straight average that does not take into account the abundance of
each isotope.
6. Neon-20 has a mass of 19.9924 amu, Neon-21 has a mass of 20.9940 amu, and Neon-22 has a mass of
21.9914 amu. The relative abundance of Ne-20 is 90.92%, Ne-21 is 0.257%, and Ne-22 is 8.82%. Calculate
the average atomic mass for neon.
7. Suppose your chemistry grade is broken down so that 40% is based on tests, 40% on Graded assignments,
and 20% on homework. Find your average score based on these individual scores: tests 78, graded
assignments 89, homework 50.
EXTRA TIME? Complete:
1. Do the experiments to determine the atomic mass of a second sample of vegium. How does it compare to
the first? Why?
2. Select three beans from your sample – the largest, the smallest, and one that appears to be average in size.
Determine the mass of each of the three. Compute the average mass of the largest and smallest, and
compare this to the mass of the “average” bean and to the average mass of beans you determined in the
experiment. Which average mass is most reliable? Why?