A ligand having an unshared pair of electrons may be a

Options

A. neutral molecule
B. positively charged ion
C. negatively charged ion
D. group containing a lone pair of electrons

Answer

To answer the question "A ligand having an unshared pair of electrons may be a," we need to understand what ligands are and their characteristics. Here’s a step-by-step solution:

### Step 1: Define Ligands
Ligands are ions or molecules that can donate a pair of electrons to a central metal atom or ion to form a coordination complex. They can be classified based on their charge and the presence of lone pairs of electrons.

**Hint:** Remember that ligands are electron pair donors.

### Step 2: Types of Ligands
1. **Neutral Molecules:** These are molecules that do not carry any charge but have lone pairs of electrons available for donation. An example is ammonia (NH₃), which has a lone pair on the nitrogen atom.

**Hint:** Look for molecules that have lone pairs but no overall charge.

2. **Positively Charged Ions (Cations):** Some cations can act as ligands by donating their electron pairs. For example, the hydronium ion (H₃O⁺) can coordinate with other species.

**Hint:** Consider ions that have a positive charge and can still donate electrons.

3. **Negatively Charged Ions (Anions):** Anions often have lone pairs of electrons that can be donated to a metal center. Examples include oxalate (C₂O₄²⁻) and sulfate (SO₄²⁻).

**Hint:** Identify ions with a negative charge that have available lone pairs.

4. **Groups Containing Lone Pairs:** Some ligands may be larger groups that contain atoms with lone pairs, such as phosphines (e.g., triphenylphosphine, PPh₃).

**Hint:** Think about larger molecular structures that can still donate electron pairs.

### Step 3: Conclusion
From the above classifications, we can conclude that a ligand having an unshared pair of electrons may be:
- A neutral molecule (e.g., NH₃)
- A positively charged ion (e.g., H₃O⁺)
- A negatively charged ion (e.g., C₂O₄²⁻, SO₄²⁻)
- A group containing a lone pair of electrons.

Thus, the answer to the question is that a ligand having an unshared pair of electrons may be a neutral molecule, positively charged ion, negatively charged ion, or a group containing a lone pair of electrons.

**Final Answer:** A ligand having an unshared pair of electrons may be a neutral molecule, positively charged ion, negatively charged ion, or a group containing a lone pair of electrons.