Compounds of fluorine heavier halogens (chlorine, bromine, and iodine) all form mono-, tri-, and pentafluorides: XF, XF, and XF. Of the neutral +7 species, only iodine heptafluoride is known. While chlorine and bromine heptafluorides are not known, the corresponding cations and , extremely strong oxidizers, are. Astatine is not well-studied, and although there is a report of a non-volatile astatine monofluoride, its existence is debated. Many of the halogen fluorides are powerful fluorinators. Chlorine trifluoride is particularly noteworthy—readily fluorinating asbestos and refractory oxides—and may be even more reactive than chlorine pentafluoride. Used industrially, ClF requires special precautions similar to those for fluorine gas
Chlorine causes: extreme inertness and reluctance to participate in chemical reactions (the noble gases, with the exception of xenon in the highly unstable XeCl and XeCl); extreme nuclear instability hampering chemical investigation before decay and transmutation (many of the heaviest elements beyond bismuth); and having an electronegativity higher than chlorine's (oxygen and fluorine) so that the resultant binary compounds are formally not chlorides but rather oxides or fluorides of chlorine. Chlorination of metals with Cl usually leads to a higher oxidation state than bromination with Br when multiple oxidation states are available, such as in MoCl and MoBr. Chlorides can be