Mass defect numbers

[ponyo]

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For mass defect & nuclear binding energy, do we need to memorise conversion factors and exact masses of protons and neutrons and so forth?

For example, if given the mass defect of a nucleus in amu or kg are we expected to calculate its binding energy in eV or J?

& should we be able to calculate the mass defect of some nucleus given its mass (to more decimal places than on the periodic table I guess)?

I get the impression that we don't usually need to memorise that kind of thing but I'm not really sure how they would ask a question about mass defect then...

 

[MShopes]

For mass defect & nuclear binding energy, do we need to memorise conversion factors and exact masses of protons and neutrons and so forth?

For example, if given the mass defect of a nucleus in amu or kg are we expected to calculate its binding energy in eV or J?

& should we be able to calculate the mass defect of some nucleus given its mass (to more decimal places than on the periodic table I guess)?

I get the impression that we don't usually need to memorise that kind of thing but I'm not really sure how they would ask a question about mass defect then...

No you don't need to know the exact masses of protons and neutrons. However, realize that the mass of neutron and proton are nearly identical and about 1 amu and that the electron is much smaller in mass than neutrons or protons. Also, neutrons are slightly heaver than protons.

And sure, you should be able to calculate the mass defect using E=MC^2, binding or rest mass energy might be given and you know the C, which is speed of light, and just plug and chug to get the mass defect or they might give you the mass defect and ask for energy. Ek stressed that you should think about this formula of E=MC^2 only if mass is created or destroyed, otherwise, just pretend it does not exist.