Topic 12: Atomic structure - 12.1 Electrons in atoms

Nature of science: Experimental evidence to support theories-emission spectra provide evidence for the existence of energy levels. (1.8)


Essential idea: The quantized nature of energy transitions is related to the energy states of electrons in atoms and molecules.

In an emission spectrum, the limit of convergence at higher frequency corresponds to the first ionization energy.

Trends in first ionization energy across periods account for the existence of main energy levels and sub-levels in atoms.

Successive ionization energy data for an element give information that shows relations to electron configurations.

Applications and skills

Solving problems using E = hv.

Calculation of the value of the first ionization energy from spectral data which gives the wavelength or frequency of the convergence limit.

Deduction of the group of an element from its successive ionization energy data.o Explanation of the trends and discontinuities in first ionization energy across a period.


The value of Planck's constant (h) and E = hf are given in the data booklet in sections 1 and 2.

Use of the Rydberg formula is not expected in calculations of ionization energy.