Which of the following elements cannot form hypervalent molecules?

• A. Carbon (C)
• B. Phosphorus (P)
• C. Chlorine (Cl)
• D. Sulfur (S)

Answer: (A)

Verified step by step guidance

1. Understand the concept of hypervalency: Hypervalent molecules contain a central atom that has more than eight electrons in its valence shell, exceeding the octet rule.
2. Recall that elements in period 3 and beyond (such as Phosphorus, Sulfur, and Chlorine) have access to d-orbitals, which allow them to expand their valence shell and form hypervalent compounds.
3. Recognize that Carbon is in period 2 and does not have available d-orbitals, so it cannot expand its octet beyond eight electrons and therefore cannot form hypervalent molecules.
4. Review examples of hypervalent molecules: Phosphorus pentachloride (PCl₅), sulfur hexafluoride (SF₆), and chlorine trifluoride (ClF₃) all demonstrate hypervalency, while carbon compounds typically obey the octet rule.
5. Conclude that among the given elements, Carbon (C) cannot form hypervalent molecules due to its inability to expand its valence shell beyond eight electrons.