Halogens ionization potentials

In addition to the THM methods, EMSL-Cincinnati has developed purge and trap methods for selected halogenated (29) and aromatic (30) compounds that are considered to be chemical indicators of industrial contamination. The methods are applicable to 47 halogenated compounds (Method 502) and 33 compounds that have ionization potentials less than 10.2 eV and that are aromatic or contain a doubly bonded carbon (Method 503). Seven of these compounds are halogenated and are also included in the method for halogenated compounds. Another method, Method 524 (31), provides for GC-MS determination of 28 purgeable volatiles. Single laboratory precision and accuracy data for these compounds are provided in the EMSL methods. 

It is generally assumed that the properties of the various families of the periodic chart change smoothly from less metallic (or more electronegative) at the top of the family to more metallic (or less electronegative) at the bottom of the family. Certainly for the extremes of the chart—the alkali metals on the left and the halogens and noble gases on the right—this Is true the ionization potentials, for example, vary in a rather monotonous way. This is not true For certain central parts of the chart, however. 

Mn ". 1.18 V) is less than that of magnesium, although the lirst and second ionization potentials are closely similar, due to the higher heat of sublimation of manganese. However, manganese is oxidized by the halogens. H+ or even H 0 to the dipositive state. 

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