# Why are Alkali Metal Ions Soluble?

I think the question needs no elaboration. Why are salts containing Group 1A cations extremely soluble in water?

I speculate that the reason involves the low charge density of those ions in a given period. Thus, they make better ion-dipole bonds with water molecules than other cations. But the sizes of the Group 1A metals vary, so an argument based on charge density fails as a generalization.

• Ions must be solvated. I think you mean why are salts of these ions generally soluble (in water). – Dissenter May 22 '16 at 2:52
• @Dissenter Sure, any salts that contain those ions. – Yunfei Ma May 22 '16 at 12:44
• – Mithoron May 22 '16 at 13:59
• @YunfeiMa There are plenty of poorly soluble alkali metal salts, even inorganic. E.g. $\ce{Li2CO3}$, $\ce{NaSb(OH)6}$, $\ce{NaMg(UO2)3(CH3COO)9}$, $\ce{NaAlSi3O8}$, $\ce{Na3AlF6}$, $\ce{KClO4}$, $\ce{K2PtCl6}$, $\ce{K2SiF6}$, $\ce{KAlSi3O8}$, $\ce{KC4H5O6}$ (potassium bitartrate), $\ce{RbClO4}$, $\ce{Rb2PtCl6}$, $\ce{Rb2SnCl6}$, $\ce{CsClO4}$, $\ce{Cs2PtCl6}$, $\ce{Cs2SnCl6}$. – aventurin May 22 '16 at 16:53