Mass Defect (1 Viewer)

[allstarr69]

hey.. i know im asking alot of questions and im really thankful for the help however ive got one more thing that i cant work out. This is to do with Quanta to Quarks

In the concept of mass defect, the mass of an isotope is LESS than the mass of its constituent parts right?
therefore how can nuclear fusion and nuclear fission both give off energy? With nuclear fusion I can see that the extra mass from the constituent parts can be given off as energy.
However in terms of nuclear fission, how can energy be released when more energy has to be put IN (in the form of mass) to the contituent parts?
Where is the flaw in my thinking...

 

[Xayma]

The total binding energy doesn't matter it is the binding energy per nucleon.

This generally goes up (Lithium I think has smaller then Helium) to Fe-58 then goes down. Which is why it still isn't completly sure what creates the heavier elements.

So by splitting a heavy nucleus into smaller ones energy goes out as it forms.

By combining Hydrogen into Helium energy is also given out as Helium has a larger binding energy per nucleon.

 

[allstarr69]

can you explain what binding energy is in simple terms?

 

[corro]

Binding Energy is the energy required to assemble separate parts into a whole. A bound system is at a lower energy level than its constituent parts.

Because a bound system is at a lower energy level, its mass must be less than its unbound constituents. Nuclear binding energy can be computed from the difference in mass of a nucleus, and the sum of the mass of the neutrons and protons that make up the nucleus. Once this mass difference (also called the mass defect) is known, Einstein's formula (E = mc²) can then be used to compute the binding energy of any nucleus.

 

[Xayma]

Binding energy is the energy needed to be converted into mass for a nucleus to break apart into it's constituents.

 

[allstarr69]

so constituent parts = MORE mass than whole part
therefore when an atom undergoes fission, the mass gained when the contituent parts are added up makes the mass defect.
the energy required to make this occur is called binding energy
I still dont know how energy is released when energy is converted into more mass of the constituent parts.

 

[Xayma]

No, the mass defect per nucleon in from Iron-58 generally gets smaller as atomic mass goes down, and generally goes down as atomic mass goes up.

 

[allstarr69]

Binding energy is the energy needed to be converted into mass for a nucleus to break apart into it's constituents.

so your saying binding energy is energy needed to break a whole into constituents. corro is saying the opposite... does it matter?

 

[Xayma]

Yes, corro is wrong, it is the energy released when the whole is assembled.

 

[allstarr69]

Yes, corro is wrong, it is the energy released when the whole is assembled.

what??? either im really mising something here or you just contradicted yourself... now you seem to agree with corro yet you said hes wrong lol
anyway it doesnt matter i sort of get the idea thanks for the help

 

[Xayma]

No Corro said it takes energy to assemble it. The binding energy is the energy required to split it up into its constituents or the energy released when the atom forms.

 

[allstarr69]

aaah i get it now thanks xayma! i would rep you but it wouldnt mean anything coz i dont have over 10 reps lol