Question

The purpose of this problem set is to reinforce your knowledge of some basic chemical concepts that are important for the origin of the elements.

1. Use the abundances of the stable isotopes of strontium and the masses of these nuclides (found at http://atom.kaeri.re.kr/nuchart/) to calculate the atomic weight of strontium. Compare the value that you get with the value shown in the periodic table found at http://www.rsc.org/periodic-table. Show your work.

2. Consult the chart of the nuclides (http://atom.kaeri.re.kr/nuchart/ ) and record the binding energy per nucleon for 1H, 32S 56Fe, 86Sr, and 238U. Explain how these values are consistent with the curve of binding energy seen in class

3. How do we know that the material that makes up our sun has been in another star?

Answer 1

To find the mass of the strontium you have to match the weight of every isotope with their abundances, after that we just have to calculate an average mass by making the sum of every mass atom multiplied by the abundance,

The colums of abundance and atomic mass comes from the web page provided, the fraction is just the percentage divided by 100.

So to know the average mass of strontium we just have to add all the values from the column that multiplies the fraction by the mass (last column)

If you do this you will get a value of 87.616 a.m.u.

The value from the online periodic table in the statement is 87.62 a.m.u.