Chapter U2.9, Problem 1TAI

Interpretation Introduction

Interpretation:

The three dimensional features of a molecule that are important in predicting smell are to be explained.

Concept introduction:

Molecules are three dimensional. A ball and stick model helps in knowing the exact arrangement of atoms in space. Each molecule has a different shape. Even if the molecules have same functional groups; their shapes may vary. Hence, they smell differently.

Answer to Problem 1TAI

The three dimensional features of a molecule that are important in predicting smell are:

• Arrangement of atoms in the molecules in space
• Overall shape of the molecule

Explanation of Solution

The three dimensional features of a molecule that are important in predicting smell are:

• Arrangement of atoms in the molecules in space - The ball and stick model shows the three dimensional arrangement of atoms in the molecule. The structural formula only gives a flat drawing of the molecule in which the atoms are arranged in a line. It does not represent the actual image of the molecule. From the arrangement of atoms in space, one can predict the smell of the molecule.
• Overall shape of the molecule - The ball and stick model also tells us about the overall shape of the molecule. Molecules with same functional groups such as geraniol, menthol and fenchol differ in shape and hence differ in smell. In geraniol, the carbon atoms are connected in long chain whereas menthol and fenchol have ring structures.

Conclusion

The structural formula of a molecule shows the molecule flat with the carbon atoms arranged in line whereas the ball and stick model shows the three dimensional structure of the molecule. This helps in better understanding the shape of the molecule and helps in predicting smell of the molecule.