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Quantum Mechanics

Atomic Structure and Spectra

Atomic spectra were among the strongest clues that microscopic systems do not radiate and absorb energy continuously. This chapter connects empirical line spectra, Rutherford’s nuclear atom, the Bohr model, and the limits of old quantum theory to the later wave-mechanical hydrogen atom.

Current Pages

Section titled “Current Pages”
  • Line Spectra introduces discrete emission and absorption lines as empirical facts that demanded atomic energy structure.
  • Balmer Formula explains the empirical integer pattern in visible hydrogen lines before a quantum atom theory existed.
  • Rydberg Formula generalizes hydrogen spectral series through inverse-wavelength differences and the Rydberg constant.
  • Thomson Model explains the diffuse positive-charge atom and why scattering made it untenable.
  • Rutherford Scattering explains the large-angle alpha-scattering evidence for the compact nuclear atom.
  • Nuclear Atom explains the compact nucleus as a conceptual shift that sharpened the stability problem.
  • Bohr Model presents Bohr’s hydrogen model as old quantum theory: historically crucial, mathematically useful, and incomplete.
  • Franck–Hertz Experiment explains how electron collisions with mercury vapor revealed discrete atomic excitation energies.
  • Sommerfeld Model explains elliptical orbits, action quantization, fine-structure successes, and why old quantum theory remained provisional.
  • Limits of Old Quantum Theory summarizes why the Bohr–Sommerfeld program had to be replaced by the modern state-observable-probability framework.

Canonical Boundary

Section titled “Canonical Boundary”

Historical pages explain why spectral lines and atomic stability demanded new physics. The modern hydrogen atom, radial equation, angular momentum, and orbitals are owned by Wave Mechanics and Model Systems and related formal pages.

Section titled “Cross-Links”

References

Section titled “References”
  • N. Bohr, “On the Constitution of Atoms and Molecules,” Philosophical Magazine 26, 1-25 (1913), DOI: 10.1080/14786441308634955.
  • E. Rutherford, “The Scattering of α and β Particles by Matter and the Structure of the Atom,” Philosophical Magazine 21, 669-688 (1911), DOI: 10.1080/14786440508637080.
  • A. Sommerfeld, “Zur Quantentheorie der Spektrallinien,” Annalen der Physik 51, 1-94 and 125-167, 1916.
  • Nobel Prize Outreach, Niels Bohr Facts.