Mass defect and binding energy
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
The masses are: proton 1.00728 u, neutron 1.00866 u, deuteron (²H nucleus) 2.01355 u. (a) Find the mass defect of deuterium. (b) Find its binding energy in MeV and joules. Solution: (a) Sum of parts: 1.00728 + 1.00866 = 2.01594 u. Δm = 2.01594 − 2.01355 = 0.00239 u. (b) BE = 0.00239 × 931.5 ≈ 2.226 MeV. In joules: 2.226 MeV × 1.602×10⁻¹³ J/MeV ≈ 3.57 × 10⁻¹³ J per nucleus. Small per nucleus — but a mole of deuterium holds ~2 × 10¹¹ J!