Which of the following statements correctly describes the Lewis dot structure of the phosphate ion in phosphoric acid, PO(OH)3?

• A. The central phosphorus atom is surrounded by three single bonds to OH groups and one double bond to an oxygen atom, with a formal charge of zero on phosphorus.
• B. The central phosphorus atom is bonded to three OH groups and one oxygen atom via triple bond.
• C. The central phosphorus atom is surrounded by three double bonds to OH groups and one single bond to an oxygen atom.
• D. The central phosphorus atom forms four single bonds to oxygen atoms, with each oxygen atom carrying a negative charge.

Answer: (A)

Verified step by step guidance

1. Identify the central atom in the phosphate ion within phosphoric acid, which is phosphorus (P), and recognize that it typically forms five bonds due to its ability to expand its octet.
2. Count the total valence electrons available: phosphorus contributes 5 electrons, each oxygen contributes 6 electrons, and consider the hydrogen atoms bonded to oxygen (each hydrogen contributes 1 electron).
3. Draw a skeletal structure with phosphorus in the center bonded to four oxygen atoms, three of which are bonded to hydrogen atoms (OH groups), and one oxygen atom not bonded to hydrogen.
4. Assign bonds: phosphorus forms single bonds to the three OH groups and a double bond to the remaining oxygen atom to satisfy the octet rule and minimize formal charges.
5. Calculate formal charges on each atom to confirm the most stable Lewis structure, ensuring phosphorus has a formal charge of zero and the overall charge of the ion is consistent with the phosphate ion's charge.