Practice question

**Quantization basis** de Broglie standing wave requires constructive interference, integer wavelengths in orbit, otherwise destructive, so only certain radii allowed r_n = n² a₀, a₀=0.53 Å, angular momentum L = n h/2π, de Broglie explains why orbits are stationary - electron wave closed on itself. E₅ = -(13.6/5²) = -0.544 eV , E₂ = -3.4 eV . Δ E = -0.544 - (-3.4) = 2.856 eV ≈ 2.86 eV . Using E_n = -13.6/n² eV, r_n = n² a₀, L = n h/2π, R = R₀ A^¹/³, BE = Δm c² and 1 u = 931.5 MeV, evaluation yields 2.86 eV, consistent with Bohr model and nuclear binding energy systematics.