Question

What is the formal charge of chlorine in perchloric aicd, `HClO_4`?

Answer 1

On chlorine, in `HClO_4`, `"perchloric acid.......?"`

Explanation:

In the molecule the charge on `Cl` is neutral. There are SEVEN valence electrons surrounding the atom, and thus with 10 inner core electrons there are 17 electrons whose charge PRECISELY balances the 17 positive charges in the chlorine atom's nuclear core.

Now perchloric is a strong acid, and in water undergoes the equilibrium....

`HClO_4(aq) + H_2O(l) rightleftharpoonsClO_4^(-) + H_3O^+`

On perchlorate anion, we conceive that the charge resides on the most electronegative element, the oxygen.....

`(O=)_3Cl-O^(-)`; of course the charge can be distributed by resonance to the other oxygen atoms.