History 181B - Class 23

History 181B: Modern Physics

Class 23 (3/14/03)
The old quantum theory of atomic structure

Navigation

Outline

Discrete spectra
    Background: Observations and apparatus
    Signatures of the chemical elements
    How are spectral lines produced? Models of oscillating electrons

Returning to Bohr's model
    Hypotheses about light emission: Transitions between orbits
    Fundamental principles: Quantization conditions
    What the (revised) model explains: Spectra, the periodic table
    Correspondence, and its tricks
    The (old) quantum theory of atomic structure

Names and terms

Primary	Secondary
discrete spectrum = line spectrum Gustav Kirchhoff (1824-1887) Robert Bunsen (1811-1899) Niels Bohr (1885-1962), NP 1922 Balmer spectrum (of hydrogen) quantum number delta E = h nu J = n (h/2 pi) = n x "h-bar" correspondence principle Copenhagen, Munich, Göttingen Arnold Sommerfeld (1861-1951) Max Born (1882-1970), NP 1954 perturbation theory, celestial mechanics	prism, diffraction grating Henry Rowland (1848-1901) Joseph (von) Fraunhofer (1787-1826) Werner Heisenberg (1901-1976), NP 1932 Wolfgang Pauli (1900-1958), NP 1945 Zeeman effect, Pieter Zeeman (1865-1943), NP 1902 Stark effect, Johannes Stark (1874-1957), NP 1919

Assignment

Cathryn Carson, "The Origins of the Quantum Theory," Beam Line (Stanford Linear Accelerator Center) 30:2 (2000): 6-19, also on the web .

    Second assignment: Read pp. 13-19.
    Why was it a radical step for Bohr to apply the quantum to atomic structure?
    What was the procedure of "quantization"? What was the correspondence principle?
    What two different routes in quantum theory led into the final formulation of a quantum mechanics?
    Extra: How is the story of Bohr's atom told here different from the conventional one from high-school chemistry or physics textbooks?