fajan's rule

Question

According to Fajan's rules, which of the following compounds is most covalent?

RankGuru · Accepted Answer

**Fajan's Rules** state that the covalent character of an ionic bond increases with the polarizing power of the cation.
Polarizing power increases with:
1. **Small Cationic Size**.
2. **High Cationic Charge**.
- Compare: $Na^+, Mg^{2+}, Al^{3+}, Si^{4+}$.
- $Si^{4+}$ has the highest charge ($+4$) and the smallest ionic radius among the series.
- Therefore, it strongly polarizes the electron cloud of the $Cl^-$ ions, resulting in maximum covalent character.

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fajan's rule

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