Question

Some chemists believe that satisfaction of the octet rule should be the top criterion for choosing the dominant lewis structure of a molecule or ion. other chemists believe that achieving the best formal charges should be the top criterion. consider the dihydrogen phosphate ion, h2po4−, in which the h atoms are bonded to o atoms. part a what is the predicted dominant lewis structure if satisfying the octet rule is the top criterion? draw the lewis structure for the ion. show the formal charges of all atoms in the correct structure. include all lone pairs of electrons.

Answer 1

Lewis structures refers to the diagrams used to signify the bonding between the atoms of a molecule and the lone pair of electrons, which may prevail in the molecule. These structures are drawn on the basis of the formal charge of each atom within the ion or molecule.

The formal charge refers to the charge assigned to an atom in a molecule, which all the electrons are shared equivalently amongst the atoms regardless of its electronegativity.

The rule for formal charge calculation is,

Formal charge = no of valency shell electron - 1/2 of the no of shared pair electron - no of lone pair electron.

So, in this case, the formal charge of P = 5 - 1/2 (10) - 0 = 0

The valence shell of P have 5 electrons. The total 5 bond is there in the given composition, so total 10 bonding electron, and there is no lone pair of electron on P atom. So, formal charge of P is 0.