Anamalous Nature of Fluorine
- Fluorine is the most reactive element among halogen. This is due to the minimum value of F–F bond dissociation energy.
- Fluorine decomposes cold dilute alkalies liberating OF2 and with conc. alkali, O2 is liberated. Under similar conditions, the other halogens will give rise to the hypohalites and halates respectively.
- It has the greatest affinity for hydrogen, forming HF which is associated due to the hydrogen bonding. Hydrofluoric acid is a weak acid whereas the other hydrohalic acids are strong acids.
…… H– F…… H– F….. H– F.
- It differs markedly from the other halogens in that it can form two types of salts with metals. NaF and NaHF2.
- The salts of HF differ from the corresponding salts of other hydracids. AgF is soluble in water while the other AgX are insoluble.
- Being strongly electronegative it can have only a negative oxidation state while the other halogens can have negative as well as positive oxidation state.
- HF attacks glass while others do not.
- Fluorine, because of the absence of d-orbitals in its valence shell does not form any polyhalides. Thus we have Ι3–, Br3–, Cl3– ions but no F3– ion.