Outline how atomic absorption spectra provide evidence for the quantization of energy states in atoms.

The diagram shows some atomic energy levels of hydrogen.

A photon of energy 2.86 eV is emitted from a hydrogen atom. Using the diagram, draw an arrow to indicate the electron transitions that results in the emission of this photon.

an atom will only absorb a photon if the photon energy corresponds to an energy difference between two of its energy states;

the absorption of energy takes places in discrete quantities (quanta);

arrow drawn downwards from \( - 0.54\) level to \( - 3.40\) level;

In (a), candidates rarely described absorption spectra, rather explaining emission spectra. There were very poor explanations of quantized energy states.

(b) was generally well answered, although a common mistake was to have the change in the wrong direction.