Eiioniiset

Eiioniiset is a term used in Finnish chemistry to describe substances that do not dissociate into ions when dissolved in a solvent, most commonly water. This contrasts with ionic substances, such as salts, acids, and bases, which release charged species upon dissolution. The word is formed from ei meaning “not,” ioni- from ion, and the suffix -iset, and it appears in Finnish chemical and materials science literature to denote non-electrolytic behavior.

In general, eiioniiset are covalently bonded molecules. They may be polar or nonpolar and often have higher molecular weights than typical electrolytes. In aqueous solutions their electrical conductivity is low relative to ionic compounds, and their effective van’t Hoff factor (i) is close to 1. This classification helps explain differences in properties such as solubility, boiling and melting points, and interactions with other substances. It is important to note that some substances labeled as eiioniiset can exhibit limited ionization under certain conditions or in specific solvents, so the designation is often approximate rather than absolute.

Examples of eiioniiset include many organic solvents and solutes such as ethanol and glucose, which do not form ions in typical aqueous solutions. A notable subset within this category is nonionic surfactants, used in detergents and cosmetics, such as alkyl polyglucosides and certain alkylphenol ethoxylates. These compounds reduce surface tension without generating significant ionic charge in solution.

Analytically, eiioniiset are distinguished from ionic substances by measurements of conductivity, and by evaluating colligative properties and dissociation behavior. The term remains mainly a descriptive category in Finnish-language chemistry to contrast non-electrolyte behavior with ionic dissociation.