Solution By Steps

Step 1: Lewis Structure of PO33-

To draw the Lewis structure of PO33-, we start by counting valence electrons: Phosphorus contributes 5, each Oxygen contributes 6, and the negative charge adds 1. Total valence electrons = 5 + 3(6) + 1 = 24.

Step 2: Lewis Structure Arrangement

Place the Phosphorus in the center, surrounded by three Oxygen atoms. Each Oxygen forms a single bond with Phosphorus, leaving one lone pair on each Oxygen.

Step 3: Formal Charges Calculation

Calculate the formal charges for each atom: Phosphorus has 5 valence electrons - 1 bond - 3 lone pairs = +1 charge. Each Oxygen has 6 valence electrons - 1 bond - 2 lone pairs = -1 charge.

Step 4: Resonance Structures

There are 3 reasonable resonance structures for PO33-. By moving the double bond around, we can create different arrangements where each Oxygen takes turns having the double bond.

Final Answer

The total number of reasonable resonance structures for the phosphite ion, PO33-, is 3.

Key Concept

Resonance Structures

Key Concept Explanation

Resonance structures are different Lewis structures that can be drawn for a molecule by moving electrons. They do not represent different molecules but rather contribute to the overall structure and stability of the compound.