MehrElektronenAtomen

MehrElektronenAtomen is a term used to refer to atoms that contain more than one electron, i.e., multi-electron atoms. In canonical usage, all neutral atoms with atomic number Z>1 fall into this category; hydrogen, with a single electron, is a notable exception.

The presence of multiple electrons makes the electronic structure substantially more complex than the hydrogen atom. Electron–electron repulsion and screening by inner electrons shift energy levels, yielding complicated spectra and chemical behavior governed by valence electrons. Consequently, energy levels cannot be solved exactly; approximate methods are used, such as the Hartree–Fock approach and density functional theory. The simple hydrogen-like Rydberg series is replaced by term symbols and configuration interaction in multi-electron atoms. Slater rules provide rough estimates of shielding and effective nuclear charge; Hund’s and Aufbau principles guide ground-state configurations, albeit with exceptions.

Relativistic effects become significant for heavy elements, requiring the Dirac equation and relativistic quantum chemistry methods. Properties of MehrElektronenAtomen—ionization energies, electron affinities, and bonding tendencies—follow periodic trends shaped by electron configuration, especially the valence shell.

In practice, the concept is central to chemistry and material science: the behavior of carbon, nitrogen, oxygen, transition metals, and beyond can be understood through their multi-electron structure and inter-electronic interactions. Historical developments in quantum mechanics progressively replaced the hydrogenic model with many-electron theories, enabling accurate predictions of spectra and bonds.