11
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