Practise explaining discrete atomic energy levels, interpreting emission and absorption spectra and calculating photon energy or frequency from level differences.
Some of the electron energy bands in a solid are illustrated in Fig. 12.1.
Fig. 12.1
In isolated atoms, electron energy levels have discrete values. Suggest why, in a solid, there are energy bands, rather than discrete energy levels.
A beam of light consists of a continuous range of wavelengths from 420 nm to 740 nm . The light passes through a cloud of cool gas, as shown in Fig. 11.1.
Fig. 11.1
The spectrum of the light emerging from the cloud of cool gas is viewed using a diffraction grating.
Explain why this spectrum contains a number of dark lines.
Some of the electron energy levels of the atoms in the cloud of gas are represented in Fig. 11.2.
Fig. 11.2 (not to scale)
Use data from (i) and your answer in (i) to show, on Fig. 11.2, the changes in energy levels giving rise to the dark lines in (a).
Four electron energy levels in an isolated atom are shown in Fig. 12.1.
Fig. 12.1
For the emission spectrum associated with these energy levels,
on Fig. 12.1, mark with an arrow the transition that gives rise to the shortest wavelength,
show that the wavelength of the transition in (i) is .