A low-pressure hydrogen discharge tube is observed through a diffraction grating
CHEMISTRY · Multi-part · CBSE · Chemistry · Structure of Atom · Structure of Atom
Problem
A low-pressure hydrogen discharge tube is observed through a diffraction grating. Four prominent visible lines appear at wavelengths 656 nm, 486 nm, 434 nm, and 410 nm.
(a) Identify the physical reason why the emitted light forms discrete lines rather than a continuous spectrum.
(b) Explain why a model in which the electron orbits the nucleus in arbitrary classical paths cannot account for the appearance of only these specific wavelengths.
(c) Describe how restricting the electron to quantized orbital states leads to discrete photon energies and therefore to the observed spectral lines.
(d) When the experiment is repeated with iron vapor, thousands of closely spaced lines are recorded. Explain why a multi-electron atom produces such a dense spectrum while still requiring quantum—and not classical—reasoning for its interpretation.