Question

1. naturally occurring strontium consists of four isotopes, sr - 84, sr - 86, sr - 87 and sr - 88.

below is the data concerning strontium:
sr - 84
0.56%
sr - 86
9.86%
sr - 87
7.00%
sr - 88
82.58%
what is the average atomic mass of strontium?

1. calculate the average atomic mass of bromine. one isotope of bromine has an atomic mass of 78.92u an

a relative abundance of 50.69%. the other major isotope of bromine has an atomic mass of 80.92u and a
relative abundance of 49.31%.

Explanation:

Step1: <Formula for average atomic mass>

The formula for average atomic mass \(M_{avg}=\sum_{i}(M_i\times a_i)\), where \(M_i\) is the atomic mass of isotope \(i\) and \(a_i\) is the abundance of isotope \(i\) (in decimal form).

Step2: <Convert abundances to decimals for strontium>

For Sr - 84: \(a_{84}=0.56\%=0.0056\), \(M_{84} = 84\) u.
For Sr - 86: \(a_{86}=9.86\% = 0.0986\), \(M_{86}=86\) u.
For Sr - 87: \(a_{87}=7.00\%=0.07\), \(M_{87}=87\) u.
For Sr - 88: \(a_{88}=82.58\%=0.8258\), \(M_{88}=88\) u.

Step3: <Calculate for strontium>

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Step4: <For bromine>

Let \(M_1 = 78.92\) u, \(a_1=50.69\% = 0.5069\); \(M_2=80.92\) u, \(a_2 = 49.31\%=0.4931\)

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Answer:

The average atomic mass of strontium is approximately \(87.71\) u. The average atomic mass of bromine is approximately \(79.91\) u.