Acidic oxide

Acidic oxides are oxides that react with water forming an acid; or react with a base forming a salt. They are oxides of either nonmetals or of metals in high oxidation states. Their chemistry can be systematically understood by taking an oxoacid and removing water from it, until only the oxide is left. The resulting oxide belongs to this group of substances.

Acidic oxides are not Arrhenius acids because they do not donate protons; they are not Brønsted–Lowry acids because they do not increase the hydrogen ion concentration of water. However, they are Lewis acids, because they accept electron pairs from some Lewis bases, most notably base anhydrides.

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