Question

Giving suitable reasons, arrange metal halides \[\ce{(M - X)}\] in the decreasing order of their ionic character.

Answer 1

1. Fluorine has the highest electronegativity among halogens, creating the largest difference with metals. This leads to maximum ionic character in \[\ce{M - F}\] bonds.
2. A larger electronegativity difference between M and halogen means a more polar and ionic bond.
3. As we move down from F to I, halogen atoms get bigger, and their electron clouds are more diffuse, so bond character shifts towards covalent.
4. Smaller halide ions (like F⁻) are less polarisable, favouring ionic bonds. Larger halides (like I⁻) get easily distorted by the metal cation, increasing covalent character.

Thus, ionic character decreases in the order:

\[\ce{M - F > M - Cl > M - Br > M - I}\]