Practice question

**De Broglie hypothesis** λ = h/p, p=mv momentum, suggests electron as wave, in Bohr model circumference 2πr = n λ, standing wave condition, n wavelengths fit into orbit, for n=6, 6 wavelengths, for n=4, 4 wavelengths, explains quantization of angular momentum L = r p = r h/λ = r h n/(2πr)= n h/2π = n ħ, physical basis for Bohr quantization. The observation that a small fraction of alpha-particles were deflected by large angles (e.g., more than 90°) indicated a small, dense, positively charged nucleus at the atom’s center. Using E_n = -13.6/n² eV, r_n = n² a₀, L = n h/2π, R =