Chapter 21, Problem 47A

Interpretation Introduction

Interpretation:

The advantages and disadvantages of four molecular models needs to be determined.

Concept introduction:

A scale model which represents the arrangement of atoms in the molecule is said to be molecular model.

Explanation of Solution

The four molecular models are:

• Molecular formula: It represents chemical symbols of the elements in the molecule and the number of atoms of each element is represented by subscript.

Advantage:

The molecular formula helps in determining the exact number of atoms of every element present in the compound.

Disadvantage:

The structures are not indicated by molecular formula.

• Structural formula: It consists of symbols of the elements and lines for the chemical bonds.

Advantage:

The identification of atoms and the structure of the compound is given by structural formula.

Disadvantage:

No indication is given about how a molecule is existed in space.

• Ball-and-stick model: It displays the three-dimensional position of the atoms and the chemical bonds present in a molecule. Differently colored spheres are used to represent atoms and are connected by rods that represents chemical bonds.

Advantage:

Ball-and-stick model conveys the structure of the molecule in space.

Disadvantage:

Helpful for small molecules only and the color-coded spheres that represents atom can be confusing.

• Space-filling model: The relative space that each atom exerts it self in is represented by space-filling model.

Advantage:

Space-filling model conveys how a molecule exists in space.

Disadvantage:

Helpful for small molecules only as the identification of atoms can be confusing if the molecule contains too many different atoms or if the molecule is too large.