Chemistry / Unit 2 Chem 0235 short lesson, about 20 seconds
Average Atomic Mass as a Weighted Average
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The idea
An element's average atomic mass is the weighted average of its isotopes' masses, each weighted by its fractional abundance.
In practice
Boron's average mass comes from combining its two isotopes' masses in proportion to how much of each isotope occurs in nature.
Where people slip
No single boron atom has this average mass — every real atom weighs close to one isotope's mass, never the blend.
Your place on the trail
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