Give two examples to show the anomalous behaviour of fluorine.

Explanation

The anomalous behaviour of fluorine, the first member of the halogen family as compared to the rest of the members is due to its very small size, very high electronegativity and absence of vacant `d`-orbitals in the valence shell. It is supported by the following points.
(i) Fluorine shows only negative oxidation state of `-1` in its compounds. The other members exhibit both positive and negative oxidation states.
(ii) Fluorine forms hexafluoride with sulphur `(SF_(6))`. No other member of the family forms hexahalide with sulphur.