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 than bromine or iodine. This can be seen from the standard electrode potentials of the X/X couples (F, +2.866 V; Cl, +1.395 V; Br, +1.087 V; I, +0.615 V; At, approximately +0.3 V). However, this trend is not shown in the bond energies because fluorine is singular due to its small size, low polarisability, and lack of low-lying d-orbitals available for bonding (which chlorine has). As another difference, chlorine has a significant chemistry in positive oxidation states while fluorine does not. Chlorination often leads to higher oxidation states than bromination or iodination but lower oxidation states to fluorination. Chlorine tends