Hovedioner

Hovedioner is a term used in electrochemistry and solution chemistry to describe the dominant ionic species in a solution that determines the principal mode of charge transport. The word is of Norwegian origin, derived from hoved (main, primary) and ioner (ions). In English-language literature the term is uncommon; researchers more often refer to dominant ions or principal ions when discussing ionic conductivity, transport through membranes, or electrolyte design.

The exact definition of hovedioner is descriptive rather than formal: it denotes the subset of ions that carry the majority of electrical current under specific conditions, with the identity of these ions depending on concentration, pH, temperature, and applied potential. This concept is useful for simplifying transport analyses in complex solutions by focusing on the ions with the greatest contribution to conductivity or to electrochemical charge transfer.

Examples include: in dilute NaCl solutions, the main ions are Na+ and Cl−; in seawater, the main charge carriers are predominantly Na+ and Cl− (with contributions from other ions such as Mg2+ and Ca2+); in lithium-ion battery electrolytes, Li+ and the accompanying anions often dominate. However, the term is not standardized, and the relative importance of ions can shift with conditions, so some researchers prefer more precise descriptors like “dominant ions” or “charge carriers.”

See also: dominant ions, ionic conductivity, charge carrier, transport modeling.