Stability of coordination compounds increases with increase in charge density of the metal ions .

Answer

To understand why the stability of coordination compounds increases with an increase in the charge density of the metal ions, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Definition of Charge Density**:
- Charge density refers to the amount of charge per unit volume around a metal ion. It is influenced by both the charge of the metal ion and its ionic radius. Higher charge and smaller radius lead to higher charge density.

**Hint**: Remember that charge density is a ratio of charge to volume.

2. **Crystal Field Theory (CFT)**:
- According to Crystal Field Theory, the interaction between the metal ion and the ligands (molecules or ions that donate electron pairs to the metal) is primarily electrostatic. The strength of this interaction is crucial for the stability of the coordination compound.

**Hint**: Think about how electrostatic forces work in attracting oppositely charged entities.

3. **Electrostatic Attraction**:
- As the charge density of the metal ion increases, the electrostatic attraction between the metal ion and the ligands also increases. This is because a higher charge density means a stronger positive charge that can attract the negatively charged regions of the ligands more effectively.

**Hint**: Visualize how a stronger magnet can attract more paperclips than a weaker one.

4. **Stronger Bonds**:
- With increased electrostatic attraction, the bonds formed between the metal ion and the ligands become stronger. Stronger bonds imply that the ligands are held more tightly to the metal ion.

**Hint**: Consider how a tightly held rope (strong bond) is less likely to break than a loosely held one.

5. **Increased Stability**:
- As the bonds become stronger due to increased charge density, the overall stability of the coordination compound increases. A more stable compound is less likely to dissociate into its components.

**Hint**: Think of stability like the structural integrity of a building; stronger connections lead to a more stable structure.

6. **Examples**:
- For instance, consider cobalt ions. Cobalt(III) (Co³⁺) has a higher charge density compared to cobalt(II) (Co²⁺). Thus, Co³⁺ forms more stable complexes with ligands than Co²⁺.

**Hint**: Use specific examples to reinforce the concept, as they can provide a clearer understanding of the theory.

### Conclusion:
In summary, the stability of coordination compounds increases with the charge density of the metal ions due to stronger electrostatic attractions leading to stronger bonds, which in turn results in greater overall stability of the compound.