Chapter U2.38, Problem 7E

(a)

Interpretation Introduction

Interpretation:

Lewis dot structure of butane must be drawn.

Concept Introduction :

Alkanes are saturated hydrocarbon with general formula C_nH_2n+2.

Butane has molecular formula C₄H_10.

Lewis dot structure is the representation of a molecule where all the valence electrons of participating atoms are shown as dots.

Answer to Problem 7E

Lewis dot structure Butane is shown below.

  

Explanation of Solution

Lewis dot structure of butane is shown in which all the C is tetravalent. There is no lone pair of electron. All the C is octet fulfilled whereas all the hydrogens are duplet.

(b)

Interpretation Introduction

Interpretation:

The number of electron domains there in butane must be explained.

Concept Introduction :

Electron domain is the regions of molecules where there are bond pairs and lone pairs of electrons. Each bond between two participating atoms has electron domains.

Answer to Problem 7E

Butane has 13 electron domains.

Explanation of Solution

  

Structure of butane is shown. Each C has 4 bonds and each H has 1 bond. Thus there are total 13 bonds which are electron domains.

(c)

Interpretation Introduction

Interpretation:

Shape of butane must be predicted.

Concept Introduction :

Shape of a molecule depends on the total number of electrons pairs including bond pairs and lone pairs on an atom.

Answer to Problem 7E

Butane has zigzag shape in which all the carbon atoms have tetrahedral geometry.

Explanation of Solution

Each carbon atom has total 4 bonds. Each carbon atom is bonded to either 2 or 3 hydrogen atoms and 1 or 2 other carbon atoms. Thus the shape of the molecule is zigzag with tetrahedral arrangements of bonds around each C atom.

(d)

Interpretation Introduction

Interpretation:

The reason for the carbon atom chain to be not straight must be explained.

Concept Introduction :

A molecule attains a shape in which repulsive interaction among bonds is minimum.

Answer to Problem 7E

Carbon atom chain in butane is not straight to stabilize the molecule.

Explanation of Solution

  

Each carbon atom has four bonds which are tetrahedrally arranged to give maximum stability to the molecule.

Thus butane doesn’t have straight chain structure.