Formal Charges?

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

I drew the structure for the HIO4 already
enter image source here

But I cant seem to figure out the charges.

1 Answer
Mar 18, 2018

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....