The atomic masses and natural abundances of the two naturally occurring isotopes of silver are shown

June 2023 NY Regents Chemistry Exam

32 The atomic masses and natural abundances of the two naturally occurring isotopes of silver are shown in the table below.

Which numerical setup can be used to calculate the atomic mass of silver?
(1) (106.905 u)(51.8) + (108.905 u)(48.2)
(2) (106.905 u)(51.8%) + (108.905 u)(48.2%)

(3) (106.905 u)(48.2) + (108.905 u)(51.8)
(4) (106.905 u)(48.2%) + (108.905 u)(51.8%)

Solution: To calculate the average atomic mass of an element, we take the atomic mass of each isotope and multiply by percent abundance in the decimal form ( divide by 100).

Average atomic mass of silver = 106.905 u)(51.8%) + (108.905 u)(48.2%)

Answer: 2

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