Which of the following molecules is a negatively charged nucleophile?

• A. $H_{2}O$
• B. ${\mathrm{OH}}_{-}$
• C. ${\mathrm{Cl}}_{-}$
• D. ${\mathrm{NH}}_3$

Answer: (C)

Verified step by step guidance

1. Step 1: Understand what a nucleophile is. A nucleophile is a species that donates an electron pair to form a new covalent bond. Typically, nucleophiles have lone pairs of electrons and can be neutral or negatively charged.
2. Step 2: Identify the charge on each molecule. Neutral molecules like H₂O (water) and NH₃ (ammonia) have lone pairs but no negative charge, while species like OH⁻ (hydroxide ion) and Cl⁻ (chloride ion) carry a negative charge.
3. Step 3: Recognize that negatively charged species are generally stronger nucleophiles because the negative charge increases electron density, making them more eager to donate electrons.
4. Step 4: Analyze each option: H₂O is neutral, NH₃ is neutral, OH⁻ has a negative charge and lone pairs, and Cl⁻ also has a negative charge and lone pairs.
5. Step 5: Conclude that the negatively charged nucleophiles among the options are OH⁻ and Cl⁻ because they both carry a negative charge and have lone pairs available for bonding.