Stability of SnCl4 and SnCl2 compared to PbCl4 and PbCl2
SnCl4 is relatively more stable than SnCl2, while the reverse is true for PbCl4 and PbCl2. This difference in stability can be explained by the electronic configurations and sizes of the elements involved.

Electronic configurations
- Tin (Sn) has a valence electron configuration of [Kr] 5s2 4d10 5p2.
- Lead (Pb) has a valence electron configuration of [Xe] 6s2 4f14 5d10 6p2.

Size of the elements
- Tin has a smaller atomic radius compared to lead due to increased nuclear charge in the same period.
- Lead has a larger atomic radius, making it more prone to form lower oxidation states.

Explanation for stability of SnCl4
- SnCl4 is more stable because tin can form up to +4 oxidation state, allowing it to utilize all its valence electrons in bonding with chlorine.
- The smaller size of tin allows it to effectively bond with four chlorine atoms, resulting in a stable molecule.

Explanation for stability of SnCl2
- SnCl2 is less stable compared to SnCl4 because tin can also form a +2 oxidation state.
- In SnCl2, only two of the valence electrons are utilized in bonding with chlorine, making it less stable than SnCl4.

Explanation for stability of PbCl4
- PbCl4 is less stable because lead prefers to form lower oxidation states due to its larger size.
- Lead tends to exhibit a +2 oxidation state, resulting in a less stable PbCl4 molecule.

Explanation for stability of PbCl2
- PbCl2 is more stable compared to PbCl4 as lead can effectively utilize its valence electrons in bonding with chlorine atoms in the +2 oxidation state.
- The larger size of lead allows it to form stable bonds with two chlorine atoms in PbCl2.