Binding energy per nucleon curve
Nuclear structure · Physics
Bohr atom
Interactive 3DElectrons orbit the nucleus in shells — switch element to see H, He and Li fill their shells.
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Study notes
(a) ²³⁵U (BE/A ≈ 7.6 MeV) fissions into two fragments near A ≈ 118 (BE/A ≈ 8.5 MeV). Estimate the energy released. (b) Four protons fuse to ⁴He (BE/A: p = 0, ⁴He = 7.07 MeV). Estimate the energy released per helium formed. Solution: (a) Gain per nucleon ≈ 8.5 − 7.6 = 0.9 MeV; × 235 nucleons ≈ 211 MeV per fission — matches the measured ~200 MeV. (b) Initial BE ≈ 0; final BE = 4 × 7.07 = 28.3 MeV. Released ≈ 28.3 MeV per helium nucleus (about 26.7 MeV after neutrino losses in the actual pp-chain) — the Sun's energy source.