Which of the following elements cannot be the central atom in a Lewis structure?

• A. Fluorine (F)
• B. Phosphorus (P)
• C. Sulfur (S)
• D. Carbon (C)

Answer: (A)

Verified step by step guidance

1. Understand the role of the central atom in a Lewis structure: it is typically the atom that forms the most bonds and is usually the least electronegative element in the molecule.
2. Recall that the central atom must be able to form multiple bonds or have available orbitals to accommodate bonding electrons, which usually excludes atoms that are highly electronegative and tend to hold onto their electrons tightly.
3. Consider the electronegativity and bonding capacity of each element: Fluorine (F) is highly electronegative and usually forms only one bond, making it unlikely to be the central atom.
4. Phosphorus (P), Sulfur (S), and Carbon (C) can form multiple bonds and have the ability to expand their octet (except Carbon, which follows the octet rule strictly), so they can serve as central atoms.
5. Conclude that Fluorine (F) cannot be the central atom in a Lewis structure because it typically forms only one bond and prefers to be a terminal atom.