Which of the following statements about oxygen and the octet rule is correct?

• A. Oxygen cannot expand its octet because it does not have available d orbitals in its valence shell.
• B. Oxygen can expand its octet by utilizing d orbitals in its third energy level.
• C. Oxygen can expand its octet only when it forms ionic compounds.
• D. Oxygen frequently expands its octet in compounds such as OCl4.

Answer: (A)

Verified step by step guidance

1. Recall the octet rule, which states that atoms tend to form bonds until they are surrounded by eight electrons in their valence shell, achieving a noble gas configuration.
2. Understand that elements in the second period of the periodic table, such as oxygen, have only the 2s and 2p orbitals available in their valence shell and do not have accessible d orbitals to expand their octet.
3. Recognize that elements in the third period and beyond can sometimes expand their octet because they have available d orbitals in their valence shell (for example, sulfur or phosphorus).
4. Analyze the given statements: since oxygen is a second-period element without d orbitals, it cannot expand its octet, so statements suggesting oxygen can expand its octet by using d orbitals or in compounds like OCl4 are incorrect.
5. Conclude that the correct statement is that oxygen cannot expand its octet because it lacks available d orbitals in its valence shell.