Which of the following elements can form compounds with an expanded octet?

• A. O
• B. P
• C. F
• D. N

Answer: (B)

Verified step by step guidance

1. Recall the octet rule, which states that atoms tend to form compounds in ways that give them eight electrons in their valence shell, resembling the electron configuration of a noble gas.
2. Understand that some elements can have an expanded octet, meaning they can have more than eight electrons around them in a compound. This typically happens with elements in period 3 or higher of the periodic table because they have available d orbitals to accommodate extra electrons.
3. Identify the elements given: Oxygen (O), Phosphorus (P), Fluorine (F), and Nitrogen (N). Note their positions in the periodic table: O and N are in period 2, F is also in period 2, and P is in period 3.
4. Since only elements in period 3 or beyond can utilize d orbitals to expand their octet, recognize that Phosphorus (P), being in period 3, can form compounds with an expanded octet.
5. Conclude that Oxygen, Fluorine, and Nitrogen cannot form expanded octets because they are in period 2 and lack accessible d orbitals, so the correct answer is Phosphorus (P).