What Is the Atomic Mass of Element A with Given Isotopes and Abundances?

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SUMMARY

The atomic mass of element A, which contains three isotopes—86A (85.909 u, 16.19% abundance), 87A (86.908 u, 7.00% abundance), and 88A (87.906 u)—can be calculated using the weighted average formula. The equation to use is (A1 x %A1) + (A2 x %A2) + (A3 x (1-(%1 + %2))). After determining the abundance of 88A as 76.81%, the calculation can be completed by substituting the values into the equation to find the atomic mass of element A.

PREREQUISITES
  • Understanding of isotopes and their atomic masses
  • Familiarity with percentage calculations
  • Knowledge of weighted averages
  • Basic algebra skills for equation manipulation
NEXT STEPS
  • Practice calculating atomic masses using different isotopes and abundances
  • Explore the concept of isotopic distribution in various elements
  • Learn about the significance of atomic mass in the periodic table
  • Study advanced topics in nuclear chemistry related to isotopes
USEFUL FOR

Students in chemistry, educators teaching atomic structure, and anyone interested in understanding isotopic calculations and their implications in the periodic table.

CMATT
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Homework Statement


Suppose the element A contains three isotopes, 86A (atomic mass 85.909 u, abundance 16.19%) 87A (atomic mass 86.908, abundance 7.00%) and 88A (atomic mass 87.906 u). What would be the atomic mass of A that would appear in the periodic table?

Homework Equations


(A1 x %A1) + (A2 x %A2) + (A3 x (1-(%1 +%2)) = answer

The Attempt at a Solution



16.19% + 7.00% = 23.19%

100% - 23.19% = 76.81% --> so that would be the 88A abundance % right?

then I'm confused from there. Please help
 
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CMATT said:
100% - 23.19% = 76.81% --> so that would be the 88A abundance % right?
Sure.
CMATT said:
then I'm confused from there. Please help
Just plug everything into the equation you have.
 

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