Questions and Answers
What is atomic weight?
the average atomic mass of an element
The formula for atomic weight involves multiplying isotope abundance by isotope mass. This can also be written as _____ abundance (turn percentage into decimal by adding decimal point to beginning) X isotope mass.
isotope
How do you calculate the atomic weight of chlorine given its isotopes and their abundances?
(0.7578)(34.969 amu)+(0.2422)(36.966 amu) = 35.45 amu
Study Notes
Atomic Weight
- Average atomic mass of an element, accounting for the naturally occurring isotopes.
Formula for Atomic Weight
- Calculation involves multiplying the abundance of each isotope (converted to decimal form) by the isotope's mass.
- The general formula:
(isotope abundance) X (isotope mass) + (second isotope abundance) X (second isotope mass).
Example: Chlorine Atomic Weight Calculation
- Chlorine isotopes: 75.78% of ^35Cl (atomic mass 34.969 amu) and 24.22% of ^37Cl (atomic mass 36.966 amu).
- Calculation:
(0.7578)(34.969 amu) + (0.2422)(36.966 amu) = 35.45 amu. - Result of calculation represents the atomic weight of chlorine.
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Description
This quiz focuses on understanding atomic weight, including its definition and the formula used to calculate it. You will also explore real-world examples, such as the isotopic composition of chlorine. Test your knowledge and improve your grasp of this fundamental chemistry concept.
