Editing Sodium hydroxide (section)

====Crystal structure====
NaOH and its monohydrate form orthorhombic crystals with the space groups Cmcm ([[Pearson symbol|oS8]]) and Pbca (oP24), respectively. The monohydrate cell dimensions are a = 1.1825, b = 0.6213, c = 0.6069 [[nanometer|nm]]. The atoms are arranged in a [[hydrargillite]]-like layer structure, with each sodium atom surrounded by six oxygen atoms, three each from hydroxide ions and three from water molecules. The hydrogen atoms of the hydroxyls form strong bonds with oxygen atoms within each O layer. Adjacent O layers are held together by [[hydrogen bond]]s between water molecules.<ref name="jacobs">{{cite journal|author=Jacobs, H. and Metzner, U. |year=1991|title=Ungewöhnliche H-Brückenbindungen in Natriumhydroxidmonohydrat: Röntgen- und Neutronenbeugung an NaOH·H<sub">2</sub">O bzw. NaOD·D<sub">2</sub">O|journal=Zeitschrift für anorganische und allgemeine Chemie|volume =597| issue =1| pages =97–106|doi=10.1002/zaac.19915970113}}</ref>