Explain why fluorine forms only one oxoacid, HOF.

Explanation

Chlorine, bromine and iodine from four series of oxoacids of the general formulae HOX, HOXO, `HOXO_2` and `HOXO_3` in which the oxidation states of halogen (X = CI, Br or I) is +1, +3, +5 and - 7 respectively. However, due to high electronegativity and small size, F cannot act as central atom in higher oxoacids such as HOFO, `HOFO_2` and `HOFO_3` in which the oxidation states of F would be +3, +5,7. It just forms one oxoacid, i.e., HOF in which the oxidation state of F is -1.