Chapter U2, Problem 1RE

Interpretation Introduction

Interpretation : The meaning of isomers is to be explained.

Concept Introduction : Isomers are molecules with different arrangement of atoms but same molecular formula.

Answer to Problem 1RE

Isomers are molecules that have the same molecular formula but different arrangements of atoms in space. There are different types of isomers. Some isomers have different structural formulas but same molecular formula.

Some isomers have same molecular formula and structural formula but different spatial arrangement of atoms. They may be mirror image of each other and cannot be superimposed on each other.

Explanation of Solution

Isomers are molecules that have the same molecular formula but different arrangements of atoms in space. There are different types of isomers. Some isomers have different structural formulas but same molecular formula. Example: 1 butanol, CH₂-CH₂-CH₂-CH₂-OH and 2 butanol, CH₃-CH₂-CHOH-CH₃ are structural isomers.

Some isomers have same molecular formula and structural formula but different spatial arrangement of atoms. They may be mirror image of each other and cannot be superimposed on each other.Example: Limonene, C₁₀H₁₆ has a mirror image isomer. The two isomers are different molecules as one smells of pine needles and other smells like citrus fruit.

Mirror image isomers are molecules that have the same molecular formula and structural formula but different smells. They are mirror image of each other and cannot be superimposed on each other.

For a molecule to have mirror image isomer, it should have a carbon atom that is attached to four different groups. Example: chlorofluoromethanol, CHClFOH. In this molecule, the carbon atom is attached to four different groups; a hydrogen, a hydroxyl group, a chlorine atom and a fluorine atom. Such molecules have mirror image isomers that cannot be superimposed on one another.

Conclusion

Isomers are important in knowing which molecule has smell and which molecule will not have smell.