Question

Lewis structures for the perchlorate ion (ClO4−) can be drawn with all single bonds or with one, two, or three double bonds. Draw each of these possible resonance forms, including any nonbonding electrons. Include the values of any nonzero formal charges. Use formal charges to determine the most important resonance structure and calculate its average bond order. slader

Answer 1

Answer:

The most important resonance structure is 4 (attached picture). Its bon order is $\frac{7}{4}$ or $1\frac{3}{4}$.

Explanation:

A picture with 4 forms of the perchlorate structure is attached. The first structure has simple bonds. The second structure contains a double bond, the third structure has two double bonds and the fourth structure has three double bonds.

Formal charge = group number of the periodic table - number of bonds (number of bonding electrons / 2) - number of non-shared electrons (lone pairs)

The formal charges in the first structure is +3 in chlorine and -1 in oxygen.

The formal charges in the second structure is +2 in chlorine, -1 in oxygen and 0 in the double bond oxygen.

The formal charges in the third structure is +1 in chlorine, -1 in the single bond oxygens and 0 in the double bond oxygens.

The formal charges in the fourth structure is 0 in chlorine, -1 in the single bond oxygen and 0 in the double bond oxygens.

The most important resonance structure is given by:

• Most atoms have 0 formal charge.

• Lowest magnitude of formal charges.

• If there is a negative formal charge, it's on the most electronegative atom.

Hence, the fourth structure is the mosr important.

The bond order of the structure is:

Total number of bonds: 7

Total number of bond groups: 4

Bond order= $\frac{7}{4} =1\frac{3}{4}$