What is the formula for perchloric acid?

Perchloric acid has a formula of HClO4, and it has a structure of a central chlorine atom surrounded by three oxygen atoms and one hydroxyl group. The chlorine is double-bonded to the three oxygen atoms and shares a single bond with the hydroxyl group.

For elements with four oxyanions such as chlorine, there is a naming sequence for acids in order of increasing number of oxygen atoms. For chlorine, this sequence is hypochlorous acid, with one oxygen atom; chlorous acid, with two oxygen atoms; chloric acid, with three oxygen atoms; and perchloric acid, with four oxygen atoms. This sequence only applies to elements with four possible oxyanions.