Question

Molecular geometry of IF2^-1 and lewis structure?

 

Answer 1

Concepts and reason

The problem is based on the concepts of VSEPR theory and Lewis structure. This is used to tell the geometry molecules taking electron pairs surrounding their central atoms into consideration. Both bond pairs and lone pairs are contributing to determining the geometry of molecules.

Fundamentals

There are certain rules for writing Lewis structure of a molecule. These rules are as follows:

1. First, draw the molecule's skeleton, keeping more electronegative atoms at the terminal position and less electronegative at the center.

2. Count the total number of valance electrons by taking the sum of each atom's valence electron.

3. Distribute electrons in such a way that the octet of every atom is complete.

4. Electrons that are not taking part in bonding are represented as dots and are known as lone pairs of that atom.

 

In \(\mathrm{IF}_{2}^{-}\), both iodine and fluorine belongs to the halogen family and have 7 electrons in the outermost valence shell. Since fluorine is more electronegative than iodine, iodine will be at the center. There are 7 valence electrons in iodine also 1 negative charge adds one more electron; thus, the total number of electrons surrounding iodine will be 8 as follows:

Two fluorine atoms can share 2 of the 8 electrons resulting \(s p^{3} d\) hybridization as follows:

According to VSEPR theory, \(s p^{3} d\) hybridization corresponds to trigonal bipyramidal geometry (TBP), which is represented as follows:

But molecular geometry describes the shape of the molecule, which is linear in this case because the effect of lone pairs cancels each other. Resultant molecular geometry is represented as follows:

Molecular geometry of \(\mathrm{IF}_{2}^{-}\) is Linear

In \(\mathrm{IF}_{2}^{-},\) hybridization is \(s p^{3} d\) therefore, according to VSEPR theory geometry is trigonal bipyramidal. The cancellation of lone pairs' resultant shape of the molecule or molecular geometry is linear.

Draw the Lewis structure by showing lone pairs on each atom so that the octet of all the atoms is complete. Therefore, Lewis structure of \(\mathrm{IF}_{2}^{-}\) is as follows:

In the Lewis structure, atoms are arranged so that more electronegative atom is at the terminal position. Terminal atoms are arranged around the central atom to form bonds that can be single, double, or triple. Non-bonding electrons are represented as dots on atoms and are known as lone pairs of electrons.