MetallIonen

MetallIonen (literally "metal ions" in German) are atoms of metallic elements that have lost or gained electrons and therefore carry a net electrical charge. In most chemical contexts the term denotes positively charged cations formed by loss of electrons, such as Na+, Ca2+ or Fe3+, though metal-containing anionic complexes also occur. Metal ions are characterized by their charge, ionic radius and electronic configuration, which determine chemical reactivity and coordination preferences.

Formation of metal ions occurs by ionization, redox reactions or dissolution of metal compounds; in solution they are typically solvated and often form coordination complexes with ligands like water, halides or organic molecules. Transition metal ions exhibit variable oxidation states and form colored complexes due to d–d electronic transitions, while s-block metal ions have more predictable +1 or +2 states.

Metal ions play essential roles in biology as enzyme cofactors (e.g., Mg2+, Zn2+, Fe2+/3+), in materials and industry as catalysts, battery components and in electroplating, and in environmental chemistry where mobility and speciation affect bioavailability. Some metal ions, particularly heavy metals (lead, mercury, cadmium), are toxic and subject to environmental regulation due to persistence and bioaccumulation.

Analytical techniques for detecting and quantifying metal ions include atomic absorption spectroscopy, inductively coupled plasma mass spectrometry and ion-selective electrodes. Chemical behavior in aqueous systems is governed by complexation, hydrolysis, redox chemistry and precipitation equilibria.