Diameter of water molecule

Value ~2.8 Å
Organism Generic
Reference D'Arrigo JS. Screening of membrane surface charges by divalent cations: an atomic representation. Am J Physiol. 1978 Sep235(3):C109-17 abstract, p.C109 right column bottom paragraph, p.C110 right column 2nd paragraph & p.C112 left column 2nd paragraphPubMed ID696813
Comments Abstract: "To arrive at a clear and atomically realistic representation of the process of ionic screening, a model with the following necessary and justifiable constraints was devised. 1) The minimum internuclear distance (IND) between a negative site on the membrane and a cation screening the site is equal to the sum of the site's "equivalent" radius (rs) + the diameter of a water molecule (≈2.8Å) + crystal radius of the cation (rc)." P.C109 right column bottom paragraph: "Because only the first layer of water molecules around a monatomic cation has energies of interaction with the cation that are large compared with the thermal energy (ref 38), the thickness of the hydration shell around an alkaline-earth cation is approximately equal to the diameter of a water molecule (~2.8 Å). (This result can differ markedly from that obtained when the so-called hydrated radius of a counterion, derived from mobility measurements (ref 38), is used (cf. Ref. 8).)" Other sources give value of 2.63 Å (Angstrom)
Entered by Uri M
ID 103723