Question

Formal Charges?

Draw the structure of periodic acid, HIO4. Optimize formal charges.

I drew the structure for the HIO4 already

But I cant seem to figure out the charges.

Answer 1

Well, `"periodic acid"` is a NEUTRAL acid....

Explanation:

And the formal charges associated with the individual atoms should reflect this neutrality. And remember, each atom has a specific atomic number, and there should be an appropriate number of electrons (inner shell) or SHARED by atoms in a covalent bond, to give the final charge on the beast.

Most of the time, we can simply deal with the valence electrons, and assess the charge directly..

`H` `", 1 valence electron"`

`I` `", 7 valence electrons"`

`O` `", 6 valence electrons"`

And so we gots `1+7+4xx6=32*"valence electrons"` to distribute.

From your diagram, around each oxygen atom there are 2 lone pairs, that's 4 electrons, and it is conceived to get a half share of the four electrons in the `O=I` bond.... Since oxygen has 2 inner core electrons, i.e. formally the `1s^2` set that is not conceived to participate in bonding, each oxygen atom is conceived to OWN 8 electrons, whose charge PRECISELY balances the 8 nucular charges that define the atom as oxygen....

And iodine owns SEVEN valence electrons under this rigmarole...and with 46 inner core electrons, its gots the negative charges to neutralize `Z=53`.

And that leaves hydrogen, `Z=1`...and there is ONE electron shared by hydrogen in the `O-H` bond. All the atoms are FORMALLY neutral, and periodic acid is a neutral molecule.

We know that periodic acid is strong,,

`HIO_4(aq) +H_2O(l) rarr IO_4^(-) + H_3O^+`

Can you assign charges in periodate anion? Where SHOULD the negative charge be..?

The standard Lewis structure of the parent acid is...`HO-I(=O)_3`..the which is consistent with formally NEUTRAL participating atoms....