Editing Sodium (section)

===Electrides and sodides===
Like the other alkali metals, sodium dissolves in ammonia and some amines to give deeply colored solutions; evaporation of these solutions leaves a shiny film of metallic sodium. The solutions contain the [[coordination complex]] [Na(NH<sub>3</sub>)<sub>6</sub>]<sup>+</sup>, with the positive charge counterbalanced by [[electride|electrons as anions]]; [[cryptand]]s permit the isolation of these complexes as crystalline solids. Sodium forms complexes with crown ethers, cryptands and other ligands.<ref>{{cite book|title=Applications of the Newer Techniques of Analysis|date=6 December 2012|editor=Ivor L. Simmons|publisher=Springer Science & Business Media, 2012|isbn=978-1-4684-3318-0|page=160}}</ref>

For example, [[15-crown-5]] has a high affinity for sodium because the cavity size of 15-crown-5 is 1.7–2.2&nbsp;Å, which is enough to fit the sodium ion (1.9&nbsp;Å).<ref>{{cite book|title=Design, Fabrication, Properties and Applications of Smart and Advanced Materials|editor=Xu Hou|publisher=CRC Press, 2016|edition=illustrated|isbn=978-1-4987-2249-0|page=175|date=22 June 2016}}</ref><ref>{{cite book|title=Anionic Polymerization: Principles, Practice, Strength, Consequences and Applications|editor=Nikos Hadjichristidis|editor2=Akira Hirao|publisher=Springer|edition=illustrated|isbn=978-4-431-54186-8|page=349|date=2015}}</ref> Cryptands, like crown ethers and other [[ionophore]]s, also have a high affinity for the sodium ion; derivatives of the [[alkalide]] Na<sup>−</sup> are obtainable<ref>{{cite journal|journal=[[J. Am. Chem. Soc.]]|last1=Dye|first1=J. L.|last2=Ceraso|first2=J. M.|author3=Mei Lok Tak|last4=Barnett|first4=B. L.|last5=Tehan|first5=F. J.|title=Crystalline Salt of the Sodium Anion (Na<sup>−</sup>)|date=1974|volume=96|issue=2|pages=608–609|doi=10.1021/ja00809a060|bibcode=1974JAChS..96..608D }}</ref> by the addition of cryptands to solutions of sodium in ammonia via [[disproportionation]].<ref>{{cite book|last1=Holleman|first1=A. F.|last2=Wiberg|first2=E.|last3=Wiberg|first3=N.|title=Inorganic Chemistry|publisher=Academic Press|date=2001|isbn=978-0-12-352651-9|oclc=48056955}}</ref>