Guess Decay Modes: A, Z, Mass Diff MeV

[steph17]

how can we guess the possible decay modes for an element with three given quantities: A, Z and mass difference in MeV

 

[mfb]

Mass difference to what?
You can check the masses of the nuclides that would be produced from the different decay modes, and see if such a decay is possible.

 

[dukwon]

Mass difference to what?

I assume "mass difference" means "mass defect", i.e. the difference between the mass of the nucleus and its component nucleons (when unbound)

 

[e.bar.goum]

Knowing A and Z and some logic will get you a very long way - the link below is a nuclear chart, coloured by decay mode. For example, a nucleus that is on the proton rich side of stability and of intermediate mass will decay in such a way that brings it closer to the valley of stability - a proton will have to turn into a neutron, so that element will probably decay via B+.

http://www.vanderbilt.edu/AnS/physics/volker/p330b/add_lecture_materials/wkb/audi_2003_decay_modes.png

 

[steph17]

Mass difference to what?
You can check the masses of the nuclides that would be produced from the different decay modes, and see if such a decay is possible.

i was taught too the equation of mass difference of calculating the difference between the initial and final masses of the nuclides, but in the question that i was given only one element was mentioned, i got confused over there. for eg mass difference of hydrogen(A=1,Z=1)= 7.289 MeV, mass difference of Nb(A=92, Z=41)= -86.448 MeV, mass difference of Rb(A=92, Z=37)=-75.12MeV

Or can we just ignore the mass difference data and calculate the neutron-proton ratio and compare it to the valley of stability?

 

[mfb]

i was taught too the equation of mass difference of calculating the difference between the initial and final masses of the nuclides, but in the question that i was given only one element was mentioned, i got confused over there.

You can look it up, if necessary.

Or can we just ignore the mass difference data and calculate the neutron-proton ratio and compare it to the valley of stability?

To get a rough estimate, yes, but it won't work for every isotope.