How to explain the mass deffect?

[mahela007]

I understand that when , say, several protons and neutron come together to from a nucleus they loose some mass and that this mass is lost as ENERGY as proven by Einstein. But does that actually mean that the protons and neutrons become a bit lighter? And is this what accounts for the mass defect (i.e why the relative atomic mass of any atom except C12 is not a whole number)?

 

[fatra2]

Hi there,

You are exactly right. The protons and neutrons, in an atomic nucleus become a bit lighter. This also explains your example with the C12 atom and many other.

By the way, as long as the nucleus is whole, the protons ans neutrons will be a little lighter. This mass defect is transformed into binding energy (energy that glues them together). This energy is the effect of the strong nuclear interaction.

Cheers