KBB Nuclear Phenomena Wrong Answer?

[wkupredental]

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Not sure if this answer is wrong or if I'm just not understanding it correctly...

In the example on page 307 of the KBB, the question asks about a parent isotope that emits a beta (-) particle, goes through gamma decay, and then goes through alpha decay. It asks you to work backwards and figure out what the original element was.

If you were working your way backwards, wouldn't you SUBTRACT one atomic number on the last one - because beta (-) means that you increase the daughter nucleus's atomic number by one.

Did I miss something? Their Solution acts like it's a beta (+) decay.

 

[rhuot11]

I dont have your book, but the way I see it is working backwards you should have alpha decay, then gamma decay, then beta (-) decay to your parent.
So the atomic number for the alpha decay should be (Z+1)-2 and your mass number should be A-4.
Reversing those you get (Z-1)+2 and A+4. That should bring you to the parent atom. I hope.
I got this because beta (-) gives you Z+1, gamma decay does not change the atom, then alpha decay changes your atomic number (Z) to (Z+1)-2. The mass number (A) also changes to A-4. Just reverse them and plug in the original A and Z numbers to get the answer. Hopefully that works for you.

 

[PhansterZ]

Not sure if this answer is wrong or if I'm just not understanding it correctly...

In the example on page 307 of the KBB, the question asks about a parent isotope that emits a beta (-) particle, goes through gamma decay, and then goes through alpha decay. It asks you to work backwards and figure out what the original element was.

If you were working your way backwards, wouldn't you SUBTRACT one atomic number on the last one - because beta (-) means that you increase the daughter nucleus's atomic number by one.

Did I miss something? Their Solution acts like it's a beta (+) decay.

WKU. Nice. My wife goes to that school.

Anyways, you're right, the solution is incorrect. They assumed the beta particle was a positron (B+) instead of the electron (B-) they stated in the question.

 

[wkupredental]

WKU. Nice. My wife goes to that school.

Anyways, you're right, the solution is incorrect. They assumed the beta particle was a positron (B+) instead of the electron (B-) they stated in the question.

Awesome! WKU is a great school! 🙂
And thanks for the answer - it seemed wrong, but I didn't know for sure.