Beta Minus Decay: A Comparison of Product Nuclei Electron Numbers

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Homework Help Overview

The discussion revolves around the interpretation of electron numbers in the context of beta minus decay and the notation used for product nuclei. Participants are examining discrepancies between two notes regarding the electron count for a product nucleus with Z+1 protons and its implications for atomic mass calculations.

Discussion Character

  • Conceptual clarification, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are questioning the clarity of the notation used in the notes, particularly regarding whether the product nucleus has Z or Z+1 electrons. They explore the implications of ionization on electron count and mass calculations.

Discussion Status

There is an ongoing exploration of the notation and its interpretations, with some participants suggesting that the texts may be attempting to convey the same concept despite their confusing wording. Guidance has been offered regarding the assumptions made about ionization and the mass of the atoms involved.

Contextual Notes

Participants note potential issues with translation and clarity in the original texts, which may contribute to misunderstandings about the concepts being discussed.

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Homework Statement


in the first photo of my note , it says that the product nucleus has Z electrons (not Z+1) electrons ,
whereas for the 2nd part of my note , it says that the atomic masses of the product nucleus( which has A nucelon mumber and Z+1 proton number) , it has one extra orbitting electrons

why the 2nd part of the note is different from the first one? the product nucleus has Z+1 electrons or Z electrons?
2. Homework Equations

The Attempt at a Solution

 

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I think they're trying to say the same thing, but the second is very poorly worded. The notation contributes to the problem.
##^A_{Z+1}Y## in the equation they both quote represents an ion, i.e. It is missing an electron. How are you supposed to know this from the notation? Shouldn't it be something like ##^A_{Z+1}Y^+##?
The first text treats it as representing an ion throughout. The second text seems to recognise the ambiguity; the references after the equation interpret it as the un-ionised atom, so needs to subtract off the mass of the electron when calculating the mass loss. I.e., ##m_y## is the mass of the un-ionised atom.
 
haruspex said:
I think they're trying to say the same thing, but the second is very poorly worded. The notation contributes to the problem.
##^A_{Z+1}Y## in the equation they both quote represents an ion, i.e. It is missing an electron. How are you supposed to know this from the notation? Shouldn't it be something like ##^A_{Z+1}Y^+##?
The first text treats it as representing an ion throughout. The second text seems to recognise the ambiguity; the references after the equation interpret it as the un-ionised atom, so needs to subtract off the mass of the electron when calculating the mass loss. I.e., ##m_y## is the mass of the un-ionised atom.

##^A_{Z+1}Y## represent positive ion am i right? but not ##^A_{Z+1}Y^+## ... the product nuclei has Z+1 proton but the number of electrons remained the same... so for ##^A_{Z+1}Y## , it's a positive ion... am i right?

i knew this from the first photo.
 
gxc9800 said:
##^A_{Z+1}Y## represent positive ion am i right? but not ##^A_{Z+1}Y^+## ... the product nuclei has Z+1 proton but the number of electrons remained the same... so for ##^A_{Z+1}Y## , it's a positive ion... am i right?

i knew this from the first photo.
Forget about the beta decay for the moment. Y represents some element. The notation ##^A_{Z+1}Y## should represent an atom of element Y, having atomic mass A and Z+1 protons. In the absence of any indication as to whether it is ionised, one would assume it therefore has Z+1 electrons. The right hand side of the equation should therefore read ##^A_{Z+1}Y^++e^-##.
Anyway, do you now understand that the two texts are trying to say the same thing?
 
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haruspex said:
Forget about the beta decay for the moment. Y represents some element. The notation ##^A_{Z+1}Y## should represent an atom of element Y, having atomic mass A and Z+1 protons. In the absence of any indication as to whether it is ionised, one would assume it therefore has Z+1 electrons. The right hand side of the equation should therefore read ##^A_{Z+1}Y^++e^-##.
Anyway, do you now understand that the two texts are trying to say the same thing?
alright, can you please look at the 2nd photo?
i can understand why the mass defect (for atomic mass) is mx -( my-me) -me , why not mx -( my+me) -me ?

before subtracting the mass of the 'extra orbitting electron' , why the mass defect is calculated by mx-my-me (just like nuclear mass at the top part ) ??
 
gxc9800 said:
alright, can you please look at the 2nd photo?
i can understand why the mass defect (for atomic mass) is mx -( my-me) -me , why not mx -( my+me) -me ?

before subtracting the mass of the 'extra orbitting electron' , why the mass defect is calculated by mx-my-me (just like nuclear mass at the top part ) ??

As I wrote, that text is taking my to be the mass of a 'complete' (un-ionised) atom of Y. Since it is ionised (+), its mass is my-me. The wording in the text is atrocious, and I'm not surprised you are confused. Is it a translation?
 
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haruspex said:
As I wrote, that text is taking my to be the mass of a 'complete' (un-ionised) atom of Y. Since it is ionised (+), its mass is my-me. The wording in the text is atrocious, and I'm not surprised you are confused. Is it a translation?
i will try my best to understand . i am not sure whether it's the translation or not. but i english is not my first languange...
 

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