List of aqueous ions by element
This table lists the ionic species that are most likely to be present, depending on pH, in aqueous solutions of binary salts of metal ions.
The existence must be inferred on the basis of indirect evidence provided by modelling with experimental data or by analogy with structures obtained by X-ray crystallography.
When a salt of a metal ion, with the generic formula MXn, is dissolved in water, it will dissociate into a cation and anions.
For convenience (aq) is not shown in the rest of this article as the number of water molecules that are attached to the ions is irrelevant in regard to hydrolysis.
[citation needed] With salts of divalent metal ions, the aqua-ion will be subject to a dissociation reaction, known as hydrolysis, a name derived from Greek words for water splitting.
[citation needed] The model is defined in terms of a list of those complex species which are present in solutions in significant amounts.
The formation of an hydroxo-bridged species is enthalpically favoured over the monomers, countering the unfavourable entropic effect of aggregation.
Therefore, when determining the stability constants of both species it is usually necessary to obtain data from 2 or more titrations, each with a different metal salt concentration.
The principal problem when determining the stability constant for a polymeric species is how to select the "best" model to use from a number of possibilities.
[6][7][8] The separate dashed boundary around the Nb-Ta-W-Tc-Re-Os-Ir hexad is an exemplar for the reputation many transition metals have for nonmetallic chemistry.
[9] Ⓐ Hydrogen is shown as being a cation former but most of its chemistry, "can be explained in terms of its tendency to [eventually] acquire the electronic configuration of…helium",[11] thereby behaving predominately as a nonmetal.
[19] Ⓙ Stein, in 1987,[20] showed the metalloid elements as occupying a zone in the p-block composed of B, Si, Ge, As, Sb, Po, Te, At and Rn.
In the periodic table image these elements are found on the right or upper side of the dashed line traversing the p-block.
Ⓚ Of 103 elements shown in the image, just ten form anions, all of these being in the p-block: arsenic; the five chalcogens: oxygen, sulfur, selenium, tellurium, polonium; and the four halogens: fluorine, chlorine, bromine, and iodine Ⓛ Anion-only elements are confined to oxygen and fluorine.
• the red cobalt cation Co 2+ from Co(NO 3 ) 2 (see § Co )
• the orange chromium oxyanion Cr 2 O 2− 7 from K 2 Cr 2 O 7 ( § Cr )
• the yellow chromium oxyanion CrO 2− 4 from K 2 CrO 4 ( § Cr )
• the turquoise nickel cation Ni 2+ from NiCl 2 ( § Ni )
• the blue copper cation Cu 2+ from CuSO 4 ( § Cu )
• the purple manganese oxyanion MnO − 4 from KMnO 4 ( § Mn )
