Mg2

Mg2+ refers to the magnesium ion carrying a two-plus charge. It is formed when magnesium atoms lose two electrons. In aqueous solution, Mg2+ predominantly exists as the hexaaqua complex [Mg(H2O)6]2+, reflecting its high charge density and preference for oxygen-donor ligands. The ion is small and a hard Lewis acid, forming strong hydration shells and high lattice and hydration energies. Its electronic configuration in Mg2+ is that of neon ([Ne]); it is diamagnetic and does not have unpaired electrons.

Occurrence and sources often include minerals such as magnesite (MgCO3) and dolomite (CaMg(CO3)2), as well as seawater and other brines. Commercial production of metallic magnesium typically involves electrolysis of molten magnesium chloride, which is derived from these sources. In solution, Mg2+ forms a variety of salts, including magnesium sulfate (MgSO4), magnesium chloride (MgCl2), and magnesium hydroxide (Mg(OH)2), the latter of which precipitates at higher pH.

Biological and chemical significance is broad. Mg2+ is an essential nutrient for all living cells, acting as a cofactor for numerous enzymes and stabilizing negatively charged structures such as ATP, nucleic acids, and ribosomes. It plays a key role in chlorophyll, where a central Mg2+ ion sits within the porphyrin ring. In coordination chemistry, Mg2+ typically adopts octahedral coordination, often as [Mg(H2O)6]2+ in solution.

Industrial and environmental notes include its contribution to water hardness and its reactivity with water and air when in elemental form. Mg2+ is widely studied and utilized in biology, chemistry, medicine, and materials science.