1. A Review of General Chemistry

Use resonance structures to identify the areas of high and low electron density in the following compounds:

(a)

(b)

(c)

Which of the following best represents a valid resonance structure for methyl isocyanate (${\mathrm{CH}}_{3}NCO$)?

Draw two important resonance structures involving the C―O π bond for the molecule shown. To which carbons would you expect a nucleophile to add?

Which of the following best describes the resonance hybrid of the acetate ion ${\mathrm{CH}}_3{\mathrm{COO}}_{-}$?

In the following sets of resonance forms, label the major and minor contributors and state which structures would be of equal energy. Add any missing important resonance forms.

(d)

(e)

Use resonance forms to show delocalization of the negative charge in the Ruhemann's purple anion.

In the following molecules, identify all pushable electron pairs.

(a)

a. Draw resonance contributors for the following species. Do not include structures that are so unstable that their contributions to the resonance hybrid would be negligible. Indicate which are major contributors and which are minor contributors to the resonance hybrid.

b. Do any of the species have resonance contributors that all contribute equally to the resonance hybrid?

1. CH₃CH=CHOCH₃

Which of the following radicals can be stabilized by resonance?

Given the resonance structure of perchloric acid ($H_1{C}_1{l}_1{O}_4$), what are the formal charges on the central chlorine atom and one of the double-bonded oxygen atoms?

Which of the following statements best describes a valid second resonance structure for the nitrite ion ${\mathrm{NO}}_2-$?

Two resonance structures are shown for each molecule. Use the arrow-pushing formalism to represent the electron flow from the structure on the left to the one on the right.

(b)

Draw two important resonance structures involving the lone pair on oxygen for the molecule shown. Which carbons are most likely to act as nucleophiles?

Each pair of structures represents two valid resonance structures. Use the arrow-pushing formalism to justify the formation of the one on the left from the one on the right.

(b)

a. Draw resonance contributors for the following species. Do not include structures that are so unstable that their contributions to the resonance hybrid would be negligible. Indicate which are major contributors and which are minor contributors to the resonance hybrid.

b. Do any of the species have resonance contributors that all contribute equally to the resonance hybrid?

12.