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.
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