Question

The ICl molecule is:
A. Purely electrovalent
B. purely covalent
C. Polar with negative end on iodine
D. None of these

Answer 1

Hint: In the ICl molecule, iodine and chlorine both belong to the \[{{17}^{th}}\] group. In the \[{{17}^{th}}\] group, chlorine is at the top as compared to the iodine position which is present at the bottom in group\[{{17}^{th}}\]. Going down to the group electronegativity of elements decreases and along the period electronegativity increases.

Complete Step by Step Solution:
In molecules ICl, both iodine and chlorine bonded with a chemical bond (can be covalent or can be ionic). Covalent further are of two types, polar and nonpolar. As Iodine and chlorine both belong to the same group in the periodic table (\[{{17}^{th}}\]), where chlorine is above as compared to iodine going down to the group.

Down the group a new subshell introduces (size increases) with equal increase of nuclear charge thus, down the group, iodine tendency to attract decreases (less electronegativity) or can say easily can release an outermost electron. Whereas chlorine which is above in the group as compared to iodine has great tendency to attract chemical bond’s electrons towards itself (great electronegativity).

Thus, there is an electronegativity difference between iodine and chlorine. So, the chlorine will attract the chemical bond's electron density toward itself (not completely) and make the bond polar, introducing partially positive (on iodine), \[{{I}^{-\delta }}\] and negative charges (on chlorine) \[C{{l}^{-\delta }}\].

Thus, ICl is neither purely ionic (electrovalent) nor purely covalent (because of electronegativity difference).
Thus, the correct option is C.

Note: Ionic bond (electrovalent) formed when there is a complete transfer of electrons towards more electronegative atoms and others have great tendency to lose an electron. Generally, the ionic bond is formed between a metal and a nonmetal (electronegativity difference greater than 1.7). While polar covalent bond formed between a metal and metal or non-metal and non-metal with some electronegativity difference (greater than 0.4).Whereas covalent bonds formed between similar atoms like two hydrogens combine with a covalent bond to give hydrogen molecule (electronegativity difference is 0 which is less than 0.4).