Halogens iodine molecule

As with the other halogens, iodine is a diatomic molecule. It is always found in nature in a combined state, often as iodide salts where it has a -1 oxidation number. Compounds in which iodine is found to have oxidation numbers of 7, 3, 5, and 1 are also well known. Iodine is prepared commercially by treatment of natural salt solutions (seawater or brines) with chlorine (a more reactive halogen), according to the reaction ... 

As one of the main difficulties of the SOCI methods lies in the electronic correlation treatment, we choose an example with a large niunber of valence electrons to correlate, namely a di-halogen molecule, in order to illustrate how main-group pseudopotentials perform for spectroscopic constants. Moreover to test the ability of the various SOCI methods to handle accurately very large spin-orbit splittings, we deal with the heaviest experimentally known, the iodine molecule. 

The cycle accounts for 20—25% of the halogen-controUed loss (M is a third body molecule). The possible contribution of naturaUy occurring iodine compounds to ozone destmction (via I and lO radicals) is being investigated (79). 

The standard entropy change for the atom-molecule reactions is in the range 5-20 mole and the halogen molecule dissociation has an eiiU opy change of about 105 e.u. The halogen molecule dissociation energy decreases from chlorine to iodine, but the atom-molecule reactions become more endothermic from chlorine to iodine, and this latter effect probably influences the relative contributions to the mechanism from chain reaction and biinolecular reaction. 

The interhalogen compounds are the bromine- and iodine-base materials. It is the larger, more positive halogen that is the reactive portion of the interhalogen molecule during the disinfection process. Although only used on a limited basis at present, there are members of this class that show great promise as environmentally safe disinfectants. 

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