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Water molecules in the first and second solvation shells can exchange places. The rate of exchange varies enormously, depending on the metal and its oxidation state. Metal aqua ions are always accompanied in solution by solvated anions, but much less is known about anion solvation than about cation solvation. [6]
The low solubility of silver iodide and lead iodide reflects the covalent character of these metal iodides. A test for the presence of iodide ions is the formation of yellow precipitates of these compounds upon treatment of a solution of silver nitrate or lead(II) nitrate. [2] Aqueous solutions of iodide salts dissolve iodine better than pure ...
The oxidation states are also maintained in articles of the elements (of course), and systematically in the table {{Infobox element/symbol-to-oxidation-state}}
Oxidation states are typically represented by integers which may be positive, zero, or negative. In some cases, the average oxidation state of an element is a fraction, such as 8 / 3 for iron in magnetite Fe 3 O 4 . The highest known oxidation state is reported to be +9, displayed by iridium in the tetroxoiridium(IX) cation (IrO + 4). [1]
Many metals react with iodine. [23] By the same token, however, since iodine has the lowest ionisation energy among the halogens and is the most easily oxidised of them, it has a more significant cationic chemistry and its higher oxidation states are rather more stable than those of bromine and chlorine, for example in iodine heptafluoride. [25]
Most metal iodides with the metal in low oxidation states (+1 to +3) are ionic. Nonmetals tend to form covalent molecular iodides, as do metals in high oxidation states from +3 and above. Both ionic and covalent iodides are known for metals in oxidation state +3 (e.g. scandium iodide is mostly ionic, but aluminium iodide is not).
For oxidation states +4 and above, only the tetrafluoride, pentafluoride and hexafluoride are known. [12] Iridium hexafluoride, IrF 6, is a volatile yellow solid, composed of octahedral molecules. It decomposes in water and is reduced to IrF 4. [12] Iridium pentafluoride is also a strong oxidant, but it is a tetramer, Ir 4 F
Nickel(II) sulfate is produced in large amounts by dissolving nickel metal or oxides in sulfuric acid, forming both a hexa- and heptahydrate [46] useful for electroplating nickel. Common salts of nickel, such as chloride, nitrate, and sulfate, dissolve in water to give green solutions of the metal aquo complex [Ni(H 2 O) 6] 2+. [47]