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Joined 2026-09-21 Message
Incoming links: Solvation shell
Hydration shell 2026-10-14
A hydration shell is a solvation shell in water. The existing hydration of ions discussion describes preferential orientations around cations and anions.
Qualitative hydration shells: opposite orientations of polar water molecules around a cation and an anion, with each ion's net electric charge retained
. Original schematic, not measured molecular positions. Atom spacings and the dashed shell boundary are illustrative. Five selected water glyphs in each panel do not assert a coordination number. Each water molecule is neutral despite its partial atomic charges. Details.
Solvation shell 2026-10-14
A solvation shell is the region of solvent constituents surrounding a solute, with local arrangements influenced by their interactions. The first solvation shell contains the closest neighbors under a stated distance or interaction criterion. A coordination number counts those neighbors; it requires such a criterion and can fluctuate. Neither a drawn ring nor a few illustrated molecules determines a measured coordination number.
In a liquid, a solvation shell is an evolving neighborhood: solvent molecules reorient and exchange with the surroundings. Different ions can produce different local dynamics. Spectroscopic measurement of hydration dynamics provides an experimental way to distinguish some of those environments without pretending that a shell is a fixed cage.