metal ion

**metal ion**

A metal ion is a positively charged atom derived from a metal element that has lost one or more electrons. These ions play essential roles in various chemical, biological, and industrial processes. In biology, metal ions like calcium (Ca²⁺), magnesium (Mg²⁺), and iron (Fe²⁺/Fe³⁺) are critical for enzyme function, cellular signaling, and oxygen transport. In chemistry and materials science, metal ions contribute to catalysis, corrosion, and the formation of coordination complexes. Understanding metal ions is fundamental in fields such as biochemistry, environmental science, and metallurgy.