Question

The maximum number of carbon atoms arranged linearly in the molecule, \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}\) are (a) 3 (b) 4 (c) 5 (d) 6

Short answer

5 carbon atoms arranged linearly.

Step-by-step solution

Identify the Structure

First, examine the given molecular structure \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}\). This molecule consists of carbon atoms connected by various types of bonds, including a triple bond and a double bond.

Count the Carbon Atoms

Next, count the total number of carbon atoms present in the linear chain of the molecule. The structure has the following carbon atoms: \(\mathrm{CH}_{3} \) (methyl group) contributes 1 carbon atom, \(\mathrm{C} \equiv \mathrm{C} \) (triple bond) contributes 2 carbon atoms, \(\mathrm{CH} \) contributes 1 carbon atom, and \(\mathrm{CH}_{2} \) (methylene group) contributes 1 carbon atom.

Sum the Carbon Atoms

Add the number of carbon atoms counted in each part of the chain. Therefore, the total number of carbon atoms in a linear arrangement is 5.

Verify the Arrangements

Finally, ensure there is no other configuration that includes more than the counted carbon atoms within the same molecule, considering the given structure constraints. Hence, the maximum number of linear carbon atoms is indeed 5.

Key concepts

Carbon Chains

Carbon chains form the backbone of organic molecules, impacting their chemical properties and reactivity. These chains are simply sequences of carbon atoms linked together, each capable of forming four bonds due to carbon's tetravalency. This flexibility allows carbon to create a vast array of structures. In the molecule \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}\), carbon atoms are arranged in a chain format, showcasing a linear configuration.
Linear chains mean the carbon atoms are consecutively bonded without any branching. Here are some characteristics of carbon chains:

• Stability: Longer chains provide greater stability to the molecule.
• Variety: Can be linear, branched, or cyclic, affecting properties of the compound.
• Flexibility: They enable diverse reactions due to various functional groups attaching to them.

Molecular Structure

Understanding molecular structure is central to grasping how a chemical compound behaves. It refers to the three-dimensional arrangement of atoms within a molecule. Commonly, visualizing this structure involves drawing a Lewis structure or chemical formula, as seen in the given molecule \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}\).The molecular structure determines several key features:

• Shape: Determines how molecules interact with each other, crucial for biological functions.
• Polarity: Impacts molecular interactions and solubility.
• Reactivity: Dictates which chemical reactions the molecule can undergo.

A clear understanding of structure helps predict molecular behavior and its potential applications.

Chemical Bonding

Chemical bonding involves the forces that hold atoms together within a molecule, crucial for molecular stability and function. In carbon chains, bonding can be covalent, involving the sharing of electron pairs between atoms.Types of bonds contribute to

• Structure: Linear, branched, or cyclic based on bond orientation and angle.
• Stability: Double and triple bonds provide different levels of stability and reactivity.
• Properties: Affect melting and boiling points, solubility, and other physical properties.

These bonds, seen in molecules like \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}\), direct interactions within and among molecules.
Understanding bonding helps predict how molecules interact and undergo transformations.

Triple Bond

A triple bond is a chemical bond where three pairs of electrons are shared between two atoms. This type of bond is stronger and shorter than single or double bonds. In our molecule,\(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}\), there is a triple bond between two carbon atoms.
Triple bonds, such as in acetylene or alkyne groups like \( \mathrm{C} \equiv \mathrm{C} \),

• Restrict rotation: Prevents the linked carbon atoms from rotating around the bond.
• Increase bond energy: Makes the molecule less reactive under normal conditions.
• Influence geometry: Cause a linear geometry at the bonding site.

Being familiar with the presence of triple bonds aids in understanding the molecule's rigidity and potential chemical reactions.

Double Bond

Double bonds involve the sharing of two pairs of electrons between two atoms, providing more stability than a single bond but less than a triple bond. They are a common feature in organic compounds and play a critical role in defining molecular shape and properties.Within the structure \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}\), there is a double bond between carbon atoms near the end of the chain. Double bonds are essential because they:

• Modify reactivity: Increase a molecule's ability to participate in chemical reactions.
• Alter physical properties: Affect melting and boiling points.
• Influence flexibility: Provide a planar configuration, unlike the linear alignment with triple bonds.

Recognizing double bonds is key in determining a molecule's potential interaction with other substances.