Alkalide ## "Normal" alkali metal compounds Alkali metals form many well-known stable salts. Sodium chloride (common table salt), Na+ Cl−, illustrates the usual role of an alkali metal such as sodium. In the empirical formula for this ionic compound, the positively charged sodium ion is balanced by a negatively charged chloride ion. The traditional explanation for stable Na+ is that the loss of one electron from elemental sodium to produce a cation with charge of +1 produces a stable closed-shell electron configuration. ## Nomenclature and known cases There are known alkalides for some of the alkali metals: [3] - Sodide or natride, Na− - Potasside or kalide, K− - Rubidide, Rb− - Caeside, Cs− Alkalides of the other alkali metals have not yet been discovered: - Lithide, Li− - Francide, Fr− ## Examples Normally, alkalides are thermally labile due to the high reactivity of the alkalide anion, which is theoretically able to break most covalent bonds including the carbon–oxygen bonds in a typical cryptand. The introduction of a special cryptand ligand containing amines instead of ether linkages has allowed the isolation of kalides and natrides that are stable at room temperature