Electronbalance

Electronbalance is a conceptual metric used to describe how electrons are distributed and redistributed within a system, typically in chemistry, materials science, and related fields. Broadly, it refers to the net electronic charge in a defined region, fragment, or subsystem relative to a reference neutral state. In practice, electronbalance can be defined as the difference between the number of electrons assigned to a region by a population analysis and the number of protons expected in that region, or as the integral of the electron density over the region minus a reference nuclear charge. The numerical value depends on the partitioning scheme chosen.

Partitioning schemes used to define electronbalance include Mulliken population analysis, Hirshfeld methods, and Bader’s atoms-in-molecules approach. Each provides a way to assign electrons to atoms or fragments, enabling a region’s electronbalance to be quantified. Electronbalance is useful for assessing charge transfer, oxidation states, and neutrality in complex systems such as molecular clusters, solids, and electrochemical interfaces.

Applications include monitoring charge transfer in chemical reactions, evaluating charge compensation in doped materials, and tracking electron redistribution during electrochemical processes. Because electronbalance depends on the chosen partitioning method and the definition of the region, it is not a unique observable; comparisons should specify the methods used.

See also: charge balance, oxidation state, redox, electron density, atoms-in-molecules. Further reading includes standard texts on population analysis and charge-partitioning methods.