Question

There are two different substances with the formula \(\mathrm{C}_{3} \mathrm{H}_{6}\). Draw both, and tell how they differ.

Short answer

They differ in structure: Propene has a double bond, cyclopropane is a cyclic compound.

Step-by-step solution

Identification

The molecular formula given is \(\mathrm{C}_{3}\mathrm{H}_{6}\). This formula suggests an alkene with a degree of unsaturation due to having two fewer hydrogens than an alkane with the same carbon count.

First Structure: Propene

Draw the structure of propene (also known as propylene), which is a linear chain:1. Three carbon atoms in a straight chain.2. A double bond between the first and second carbon atoms.3. Saturate remaining valences with hydrogen atoms.The structure: \(\mathrm{CH}_2=\mathrm{CHCH}_3\).

Second Structure: Cyclopropane

Draw the structure of cyclopropane, which forms a cyclic structure: 1. Arrange three carbon atoms to form a triangle. 2. Each carbon atom should have two hydrogen atoms attached. The structure: A triangle with each vertex (carbon) attached to two hydrogen atoms.

Comparison

The two structures differ mainly in their connectivity. Propene is a linear alkene with a double bond, making it part of the alkene family. Cyclopropane, on the other hand, forms a cycle with no double bonds, placing it in the cycloalkane family. They are structural isomers, sharing the same formula but differing in the arrangement of atoms.

Key concepts

Structural Isomers

Structural isomers are fascinating molecules with the same molecular formula, but a different arrangement of atoms. This difference in structure allows isomers to have varied physical and chemical properties. Think of structural isomers as different designs using the same building blocks, with each design providing unique characteristics. For the molecular formula \( \mathrm{C}_{3}\mathrm{H}_{6} \), concepts of unsaturation play a crucial role. This formula implies some sort of structural modification from the typical saturated alkane framework, which usually follows \( \mathrm{C}_{n}\mathrm{H}_{2n+2} \).Understanding these variances in structure is essential in organic chemistry, as it helps determine the behavior of compounds during reactions. In the exercise, the two isomers, propene and cyclopropane, demonstrate different connectivity despite having the same number of atoms of each type.

Alkenes and Cycloalkanes

Alkenes and cycloalkanes showcase two major groups of hydrocarbons, differing in their structure; one having double bonds, the other forming rings.

• Alkenes: Alkenes are characterized by the presence of a carbon-carbon double bond, which grants these compounds a degree of unsaturation. The simplest alkene with the formula \( \mathrm{C}_{3}\mathrm{H}_{6} \) is propene, having a linear arrangement.
• Cycloalkanes: Cycloalkanes, on the other hand, surrender double bonds to form closed rings. Cyclopropane serves as an example where three carbon atoms form a triangular ring, securing the same molecular formula, \( \mathrm{C}_{3}\mathrm{H}_{6} \).

This difference in structure gives rise to contrasting properties and reactivity, making alkenes and cycloalkanes distinct families within hydrocarbons.

Molecular Structure Identification

In organic chemistry, identifying molecular structures relies on understanding the arrangement of atoms and the types of bonds between them. This involves recognizing patterns in molecular formulas and predicting possible structural outcomes.To identify structures like those in the \( \mathrm{C}_{3}\mathrm{H}_{6} \) molecular formula, you should:

• Analyze the formula for signs of unsaturation (missing hydrogens as compared to alkanes).
• Consider all potential arrangements of the same number of atoms.
• Assess connectivity, keeping in mind isomer possibilities.

Proper molecular structure identification helps us understand what sort of chemistries each molecule can show in reactions. Thus, knowing how to analyze and compare similar formulas empowers students to predict the behavior and properties of various compounds accurately.