Q10.81CP - Chemistry: Molecular Nature Of Matter And Change

Question

Perchlorates are powerful oxidizing agents used in fireworks, flares, and the booster rockets of space shuttles. Lewis structures for the perchlorate ion  $\left({\mathbf{ClO}}_4\right)$ can be drawn with all single bonds or with one, two, or three double bonds. Draw each of these possible resonance forms, use formal charges to determine the most important, and calculate its average bond order.

Step-by-Step Solution

Answer

Bond order in perchlorate is  $\mathbf{1}\mathbf{.}\mathbf{75}$

 

Step 1: Resonance structures

In perchlorate ion, total number of valence electrons are 32.  The number of valence electrons in chlorine is seven and number of valence electrons in oxygen is six. In perchlorate ion there is   formal charge is present.In this molecule, chlorine presents at center and bonded with three oxygen atoms through double bonds and with rest of one oxygen atom through single bond. Molecular structure of perchlorate ion is resonance stabilised. It forms four resonance structures which are drawn below

Step 2: bond order Definition:

Bond order is the number of bonding pairs of electrons between two atoms

 

Bond order of Cl-O bond is =  $\frac{\mathbf{total}\mathbf{number}\mathbf{of}\mathbf{bonds}\mathbf{around}\mathbf{chlorine}}{\mathbf{number}\mathbf{of}\mathbf{resonating}\mathbf{structures}}$

 

 $\mathbf{=}\frac{7}{4}\mathbf{=}\mathbf{1}\mathbf{.}\mathbf{75}$