Correct Answer: C
Explanation:
A nucleophile is a species that donates a pair of electrons to form a new covalent bond. Nucleophilicity is measured by comparing reaction rates; the faster the reaction, the better (or, “stronger”) the nucleophile.
For our purposes, there are at least four key factors contributing to nucleophilicity.
- Charge
- Electronegativity
- Solvent
- Steric hindrance
Assuming an atom has a pair of electrons to donate, the ability of a species to donate that pair should be inversely proportional to how “tightly held” it is. The key factor for determining how “tightly held” an electron pair is
bound is the familiar concept of electronegativity. Bottom line: as electronegativity increases, nucleophilicity decreases. Note: It’s important to restrict application of this trend to atoms in the same row of the periodic table; for instance, C N O F.