Alpha-particle scattering and the nuclear atom, and the failure of the classical atom. Then atomic spectra and the hydrogen series, Bohr's postulates and energy levels with their derivations, and de Broglie's explanation of the orbits.
3 lessons, about 1 h 30 min3 simulations11 problems6 practice questionsPython in every lesson
Created by StemPy LabRutherford's team fired alpha particles at a gold foil. Most went straight on, but a few turned back, so the positive charge and nearly all the mass sit in a tiny nucleus. An alpha particle fired head-on reaches . A classical atom with orbiting electrons would collapse.
Bohr allowed only orbits with angular momentum . Equating the electric force to then gives , and . de Broglie's waves explain the rule.
Hot gases give out only certain wavelengths. For hydrogen, with . Each gives a series: Lyman, Balmer, Paschen, Brackett and Pfund. Bohr's levels explain the formula and the value of .
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