Which stable nuclides exist
Remember: Nuclei are composed of N neutrons and Z protons – collectively A = N + Z nucleons; for example:
The heaviest stable element is lead-208,
How many protons and neutrons in this nucleus?
It was once believed there were 90 naturally-occurring elements between hydrogen (Z = 1) to uranium (Z = 92). Is there anything odd about this? (answer)
Generally all elements beyond Z = 92 are man-made. So far (as of February 2019) the record is Z = 118.
Use this spreadsheet with information for the most stable abundant isotope of the first 82 elements (up to Lead). Download the spread sheet and use the data to plot Number of protons (x) vs Number of Neutrons (y). Watch this video if you are not sure how to do this in Excel.
Discussion
1. Describe the shape of the graph and how it compares to the x=y graph
2. Use the filters on the spread sheet to examine the difference between even and odd number of protons and number of stable isotopes. Can you see pattern? What might this suggest?
3. Why do you think larger atoms need more neutrons than protons to remain stable?