Open Question
Argon has three naturally occurring isotopes, with mass numbers 36, 38, and 40.d. Why is the atomic mass of argon listed on the periodic table not a whole number?
2. Atoms and the Periodic Table
Atomic Mass (Simplified)
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Silver has an atomic mass of 107.868 amu. The Ag-109 isotope (108.905 amu) is 48.16%. What is the amu of the other isotope?
A
106.905 amu
B
106.908 amu
C
106.903 amu
D
106.911 amu
Verified step by step guidance1
Understand that the average atomic mass of silver is given as 107.868 amu, which is a weighted average of its isotopes.
Recognize that the problem provides the mass and abundance of one isotope, Ag-109, which is 108.905 amu and 48.16% abundant.
Let the mass of the other isotope be denoted as x amu, and its abundance will be 100% - 48.16% = 51.84%.
Set up the equation for the average atomic mass: (108.905 amu * 0.4816) + (x amu * 0.5184) = 107.868 amu.
Solve the equation for x to find the atomic mass of the other isotope.
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