Calculating Average Atomic Mass
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Objective
I can calculate the average atomic mass of an element given the masses and abundances of its isotopes.
Part 1 of 4
Warm-up video
Tyler DeWitt · 13:19
We don't generate video — this one is by Tyler DeWitt on YouTube. The practice questions and exit ticket below were drafted by AI for this objective, and every question is editable in the teacher guide.
Part 2 of 4
Key concepts
3 concepts
- 1
Atomic mass is a weighted average of the masses of different isotopes of an element.
- 2
Isotopes of an element have the same number of protons but different numbers of neutrons.
- 3
To calculate the weighted average, multiply the mass of each isotope by its percent abundance (expressed as a decimal) and then add those values together.
Part 3 of 4
Practice
3 questions
What is the main difference between a regular average and a weighted average, as explained in the video?
Element X has two isotopes: X-200 with a mass of 200 amu and an abundance of 20%, and X-202 with a mass of 202 amu and an abundance of 80%. Calculate the average atomic mass of element X.
Part 4 of 4
Exit ticket
Quick comprehension check
“Element X has two isotopes: X-200 and X-202. If the abundance of X-200 is 60% and the abundance of X-202 is 40%, calculate the average atomic mass of element X. Show your work.”
Sample answer included in the free materials
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