Which of the following statements correctly describes the Lewis dot structure for the PO_2^- ion?

• A. Phosphorus is the central atom, bonded to two oxygen atoms, both with double bonds, and the negative charge is on the phosphorus atom.
• B. Phosphorus is the central atom, bonded to two oxygen atoms, with one triple bond and one single bond, and the negative charge is on the triply bonded oxygen.
• C. Phosphorus is the central atom, bonded to two oxygen atoms, with one double bond and one single bond, and the negative charge is located on the singly bonded oxygen.
• D. Phosphorus is the central atom, bonded to two oxygen atoms, both with single bonds, and the negative charge is shared equally between the two oxygens.

Answer: (C)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons for the PO_2^- ion. Phosphorus (P) has 5 valence electrons, each oxygen (O) has 6 valence electrons, and the negative charge adds 1 extra electron. So, total valence electrons = 5 + 2×6 + 1 = 18 electrons.
2. Step 2: Identify the central atom, which is phosphorus, because it is less electronegative than oxygen and can form multiple bonds.
3. Step 3: Connect the phosphorus atom to the two oxygen atoms with single bonds initially, using 2 electrons per bond (4 electrons total).
4. Step 4: Distribute the remaining electrons to satisfy the octet rule for the oxygen atoms first, then place any leftover electrons on the phosphorus atom. Adjust bonding by forming double bonds if necessary to complete octets and minimize formal charges.
5. Step 5: Calculate formal charges for each atom to determine the most stable Lewis structure. The correct structure will have the negative charge localized on the singly bonded oxygen atom, with phosphorus bonded to one oxygen by a double bond and to the other oxygen by a single bond.