Chapter 27, Problem 17Q

To determine

Why spectra of Lyman series only observed when light passes through the hydrogen gas at room temperature.

Answer to Problem 17Q

Solution:

In hydrogen gas transitions involving in the ground state.

Explanation of Solution

Lyman series:

     The energy level differences in hydrogen gas follow distinct and recognizable patterns. All the downward transitions that end in the n=1 ground state corresponds to wavelengths in the ultraviolet range of spectrum. This group is known as Lyman series. The series limit for the Lyman series corresponds to nwith a wavelength 912A°

    At room temperature, nearly all the atoms of hydrogen gas will be in the ground state. When light passes through the gas, an electron in the ground state (n=1)absorbs the photon with wavelength912A°, the electron becomes unbound and it transitions to higher states and creating absorption line.