Halogens perhalic acids

Iodine differs from the other halogens because it forms more than one perhalic acid. Paraperiodic acid (HsIOg) is obtained as white crystals (mp 128°C) when periodic acid solutions are evaporated. When heated to 100°C at reduced pressure, these crystals lose water and are converted to metaperiodic acid (HIO4) ... 

Chlorous acid, HCIO2, is the only known halous acid. All the halogens except fluorine form halic and perhalic acids. The Lewis structures of the chlorine oxoacids are... 

For a given halogen, the acid strength decreases from perhalic acid to hypohalous acid the explanation of this trend is discussed in Section 15.9. 

Halates are readily prepared by the base hydrolysis of the halogen. Bromates and iodates can also be synthesized by the oxidation of the halide. Only iodic acid can be isolated outside of aqueous solution. Chlorates are excellent oxidizing agents, lodate occurs naturally, is a source of elemental iodine, and is a primary standard for iodimetry. The perhalic acids of chlorine and iodine are much easier to prepare than that of bromine. Perchloric acid, like sulfuric and phosphoric acid in previous groups, has a tetrahedral structure around the central atom and involves dir-pir... 

All of the halogens form oxoacids. The perhalic acids have the general formula of HXO4. Explain why HCIO4 is a much stronger acid than HIO4. 

In the perhalic acids, HXO4, where X = Cl, Br, or I, the halogen atom forms seven bonds, four of which are sigma bonds and three of which are ti bonds. The Lewis structure for perchloric acid is shown below. 

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