Chapter 2, Problem 2.36E

(a)

Interpretation Introduction

Interpretation:

Two of the three possible Lewis structures of ${\text{C}}_3{\text{H}}_4$ has to be drawn.

Concept Introduction:

Lewis structures represent covalent bonds and describe valence electrons configuration of atoms. The covalent bonds are depicted by lines and unshared electron pairs by pairs of dots. The sequence to write Lewis structure of some molecule is given as follows:

• The central atom is identified and various other atoms are arranged around it. This central atom so chosen is often the least electronegative.
• Total valence electrons is estimated.
• single bond is first placed between each atom pair.
• The electrons left can be allocated as unshared electron pairs or as multiple bonds around symbol of element to satisfy the octet (or duplet) for each atom.
• Add charge on overall structure in case of polytatomic cation or anion.

(b)

Interpretation Introduction

Interpretation:

The bond angles in ${\text{C}}_3{\text{H}}_4$ has to be given.

Concept Introduction:

Refer to part (a).

(c)

Interpretation Introduction

Interpretation:

The hybridization of each carbon atom in ${\text{C}}_3{\text{H}}_4$ has to be drawn.

Concept Introduction:

A single bond is always associated with sigma bonds. Molecules that have all atoms connected by sigma bond exclusively are stated to be in $s{p}^3$ hybridization. It has bond angle of $109.5°$. A double bond and carbocation are associated with $s{p}^2$ hybridization. It has bond angle of $120°$. A triple bond is always associated with $sp$ hybridization. It has bond angle of $180°$.

(d)

Interpretation Introduction

Interpretation:

Whether the two structures indicated are resonance structures or not has to be determined and reason behind it has to be explained.

Concept Introduction:

A single bond is always associated with sigma bonds. Molecules that have all atoms connected by sigma bond exclusively are stated to be in $s{p}^3$ hybridization. It has bond angle of $109.5°$. A double bond and carbocation are associated with $s{p}^2$ hybridization. It has bond angle of $120°$. A triple bond is always associated with $sp$ hybridization. It has bond angle of $180°$.