Introduction:
When certain compounds dissolve in water, they dissociate into their constituent ions. However, the dissociation pattern can vary depending on the nature of the compound and the strength of the bonds present. In the case of Hg2Cl2 and Ag2Cl2, despite both compounds having metallic bonds, their dissociation patterns differ.

Explanation:
Dissociation of Hg2Cl2:
- Hg2Cl2 is a compound composed of mercury (Hg) and chlorine (Cl) ions.
- In the solid state, Hg2Cl2 exists as a lattice held together by metallic bonds between the Hg atoms.
- When Hg2Cl2 dissolves in water, the metallic bonds between the Hg atoms break, resulting in the release of Hg2(2+) ions.
- The Cl ions remain intact and are attracted to the positively charged Hg2(2+) ions, forming Hg2(2+) and 2Cl(1-) ions in the solution.

Dissociation of Ag2Cl2:
- Ag2Cl2 is a compound composed of silver (Ag) and chlorine (Cl) ions.
- Similar to Hg2Cl2, Ag2Cl2 also possesses metallic bonds between the Ag atoms in the solid state.
- However, when Ag2Cl2 dissolves in water, the dissociation pattern is different.
- The metallic bonds between the Ag atoms break, resulting in the release of Ag(+) ions.
- The Cl ions also dissociate from the compound, resulting in the release of 2Cl(-) ions.
- Thus, the dissociation of Ag2Cl2 in water produces 2Ag(+) and 2Cl(-) ions.

Explanation for the difference:
The difference in the dissociation patterns of Hg2Cl2 and Ag2Cl2 can be attributed to the different strengths of their metallic bonds.
- The metallic bond in Hg2Cl2 is relatively weaker compared to that in Ag2Cl2.
- As a result, the metallic bonds in Hg2Cl2 are more easily broken when the compound is dissolved in water.
- On the other hand, the metallic bond in Ag2Cl2 is stronger, requiring more energy to break.
- Consequently, Ag2Cl2 dissociates into Ag(+) and Cl(-) ions, with the metallic bond remaining intact.

Summary:
In summary, the dissociation pattern of a compound when dissolved in water depends on the strength of its metallic bond. While Hg2Cl2 dissociates into Hg2(2+) and 2Cl(1-) ions due to the relatively weaker metallic bond, Ag2Cl2 dissociates into 2Ag(+) and 2Cl(-) ions, with the metallic bond remaining intact due to its stronger nature.