5
The Curve of
Binding Energy
•If you keep adding protons to a
nucleus?
–Coulomb repulsion continues to
increase
•new proton feels repulsion from all other protons
–Strong force attraction reaches limit
•new proton can’t feel attraction
from protons on
far side of a big nucleus
•Gain energy only up to point where Coulomb repulsion outweighs strong force attraction.
•Most “stable” nucleus is 56Fe
(26 protons, 30 neutrons, 56 total)
(26 protons, 30 neutrons, 56 total)
•Release energy by fusion of light nuclei to make heaver ones– up to 56Fe
•Release energy by fission of heavy nuclei to make lighter ones – down to 56Fe
From our text: Horizons, by Seeds