The Average Atomic Mass of Beanium
Claim: The average atomic mass of an element can be determined using a weighted average of
the isotopic composition of the element.
Evidence: The isotopic composition of “beanium” was determined by counting the number of
each type of isotope, finding the average mass of each isotope, and determining the percent
abundance and relative abundance. The relative abundance of each isotope was multiplied by
its average mass to find the relative mass of each isotope. The relative masses were added to
find the average atomic mass of “beanium”.
The white bean isotope had a relative mass of 0.61 amu, the black bean iostope had a relative
mass of 0.68 amu, and the lima bean isotope had a relative mass of 0.16 amu. The average
atomic mass of beanium was determined to be 1.45 amu
The black bean isotope made up the largest percentage of the “beanium” at 49%,
followed by the white beans at 43%, and the lima beans with the smallest percentage at 8%.
Although the lima beans had the largest average mass (1.59 amu), they made the smallest
contribution (0.16 amu) to the average atomic mass of beanium beause they were present in
the smallest amount.
The average atomic mass is the sum of the relative masses of each isotope, which are
based on the relative abundance of each isotope in the sample of beanium and the average
mass of each isotope. The average atomic mass of an element is a weighted average which
takes into account the relative abundance and relative mass of each isotope.
Claim – What is the purpose of the lab? What will be done?
Evidence – How was the data collected and how was it analyzed? summarize the procedure,
summarize the data
Interpretaton – What conclusion was drawn from the data? What results were obtained and
how do they support the claim (hypothesis)