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23. Inconsistencies
   Has anybody heard of hexavalent oxygen? Or heptavalent fluorine? No, nobody has ever heard of them.

   We don't like to be pessimists but we can say quite confidently that chemistry will never know such ions of oxygen and fluorine.

   There is no reason under the sun why these elements should shed such a large number of electrons when all they need is to acquire two or one to form a stable octet electron shell. That is why very few compounds are known in which oxygen exhibits positive valence. For example, an oxide of the composition F2O has been obtained where oxygen is positively bivalent. But this is exotics, as far as chemistry is concerned. Compounds of positively valent fluorine are also very rare.

   One of the items of the "Big House Regulations" states that the highest positive valence of an element shall be equal to the number of the group it belongs to.

   Though oxygen and fluorine break this rule, they have been registered permanently in the sixth and seventh groups. Nor has anyone ever thought of moving them; because in all other respects the chemical behaviour of oxygen and fluorine does not differ from the way of life of their heavier neighbours on the other floors of the Big House.

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