In: Chemistry
Which nuclides are predicted to be unstable? 92Pd, 263Sg, or 166Nd. I did the N/P ratios and got 1, 1.48, and 1.77, respectively. I thought Nd would be the only unstable one because Pd's is a perfect 1 and Sg (a larger nuclei) is very close to 1.5. But my answer key says they are all unstable. Why?
The stability of the nuclide depends on the ratio N/P (according to the stability band)
A nuclei with an even number of protons and neutrons are likely to be stable.
If there are the following amount of
proton: 2, 8, 20, 28, 50, 82, 114
neutron: 2, 8, 20, 28, 50, 82, 126, 184
the nucleus is likely to be stable
Pd 92, Pd has an atomic number of 46, there are 46 protons
92 - 46 = 46 neutrons
N/Z = 1
this value of N/Z is too low for this region of the band so this one is unstable
Sg 263
Atomic number = 106
neutrons = 263 - 106 = 157
N / P = 157 / 106 = 1.48
but at this point (very high atomic mas) there are no stable isotopes , elements with Z > 83 (number of protons) are radioactive and unstable
Nd 166
Nd atomic number 60
neutrons = 166 - 60 = 106
N/P is 1.77
in this band of region it is unstable
the N/P = 1 rule applies for low atomic number elements (lower than 20) as you increase the atomic number the N/Z ratio has to be slightly greater than 1 to be stable.
You can confirm these answers by looking at the stability band, you can find the chart easily on a book
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