The elements of this group form a number of compounds with halogens.

The halogen compounds of S. Se, Te and Po are called as halides. For oxygen, only the fluoro compounds are called as fluorides while the chloro, bromo and iodd compounds are designated as oxides. This is because of the high electronegativity of oxygen which is exceeded only by fluorine. You will study the oxides of halogens in the following unit.

All binary compounds of oxygen with halogens are covalent. They are unstable except OF₂ and I₂O₅. All, except fluorides of oxygen, are formally acid anhydrides or mixed acid anhydrides. Many of the halogen oxides react with water to give the corresponding oxoacid or a mixture of oxoacids. They also react with bases to give the salt of a mixture of salts of the corresponding oxoacids :

Cl₂O + H₂O --------------> 2HOCl

2ClO₂ + 2NaOH -----------> NaClO₃+ NaClO₂+ H₂O

Te and Po compounds with all the halogens are known except iodides of S and Se and fluorides of Po. The salient features of these and structures of some important compounds are given here.