Question

Using lines, solid wedges, and dashed wedges, draw the three-dimensional shape of chloromethylacetylene, \(\mathrm{C}_{3} \mathrm{H}_{3} \mathrm{Cl}\). Indicate the numeric value of all bond angles.

Short answer

The three-dimensional structure of chloromethylacetylene (C3H3Cl) can be represented as: H 180° / C≡C-C-Cl 180° 180° The molecule has a linear arrangement with bond angles of 180° between H-C≡C, C≡C-C, and C-C-Cl.

Step-by-step solution

Draw the Central Carbon Atoms

First, draw a line to represent the triple bond between the two carbon atoms and a single bond connecting the central carbon atom (C) with the other carbon atom (C) in a linear arrangement: C≡C-C

Add the Hydrogen Atom

Now, let's add the hydrogen atom (H) connected to the first carbon atom by a single bond. Since this hydrogen bond would be coming out of the plane, we draw it using a solid wedge: H / C≡C-C

Add the Chlorine Atom

Next, draw the chlorine atom (Cl) bonded to the last carbon atom in linear arrangement by a single bond: H / C≡C-C-Cl

Indicate Bond Angles

Now, we will indicate the numeric values of the bond angles. In this molecule, there are three atoms involved: hydrogen (H), carbon (C), and chlorine (Cl). - The bond angle between H, the first C, and the second C is 180° because of the linear arrangement. - The bond angle between the first C, the second C (in the triple bond), and the third C is also 180° because of the linear connection. - The bond angle between the second C, the third C, and Cl is also 180°, again due to the linear arrangement. Add these angle values to the drawing: H 180° / C≡C-C-Cl 180° 180° The final representation of the chloromethylacetylene molecule (C3H3Cl) is as follows: H 180° / C≡C-C-Cl 180° 180°

Key concepts

Three-Dimensional Molecular Drawing

Creating a three-dimensional molecular drawing helps us visualize molecules beyond their flat, two-dimensional representations. In the case of chloromethylacetylene (\(\text{C}_3\text{H}_3\text{Cl}\)), understanding its three-dimensional arrangement is crucial.

To depict this, we use different types of lines: solid lines (or plain lines) represent bonds lying in the plane of the paper, solid wedges show bonds coming out towards the observer, and dashed wedges indicate bonds going away from the observer. This method gives a realistic view of how atoms are arranged around a central atom, helping us predict molecular geometry and spatial arrangement in a way that a simple line drawing cannot convey.

Constructing such three-dimensional drawings is an essential skill for chemists as it aids in understanding the actual geometry and potential reactivity of the molecule.

Bond Angles

Bond angles are the angles formed between three atoms across at least two bonds. In chloromethylacetylene, each bond angle gives us clues about the molecular geometry and can impact how the molecule reacts chemically.

In a linear molecular structure like chloromethylacetylene, the bond angles are straightforward. For instance, the hydrogen (H), the two central carbons (C), and the chlorine (Cl) all form angles of 180°. This 180° angle provides the molecule with a linear shape.

Knowing bond angles is crucial for predicting how molecules will interact in chemical reactions because angles can influence the physical and chemical properties of the substance, including boiling points, polarity, and intermolecular forces.

Carbon-Carbon Triple Bond

The carbon-carbon triple bond is an important feature in molecules like chloromethylacetylene. A triple bond consists of one sigma bond where two electron clouds overlap head-on, and two pi bonds where the electron clouds overlap side-on. In structural diagrams, this is represented by three lines between the two carbon atoms: \(\text{C}\equiv\text{C}\)

This type of bond is known for being very strong and short. It significantly restricts the rotation around the bond axis, giving the molecule a rigid structure. This rigidity contributes to the linear shape of chloromethylacetylene, which is preserved in its three-dimensional drawing.

Carbon-carbon triple bonds are also sites of high reactivity, making them important in many chemical reactions. Understanding these bonds helps in comprehending the molecule's stability and reactivity.

Solid and Dashed Wedge Notation

In structural chemistry, solid and dashed wedge notation is used to depict the three-dimensional orientation of atoms around a central molecule.

For chloromethylacetylene, wedges help us visualize which atoms are located above or below the plane of the paper. A solid wedge is used to represent a bond coming out towards the observer, while a dashed wedge symbolizes a bond going into the plane, away from the observer.

This notation depicts the spatial arrangement accurately, suggesting how the molecule might interact with other molecules in three-dimensional space. This notation is especially important for complex molecules, where understanding stereochemistry—the study of the spatial arrangement of atoms—is crucial for predicting molecular behavior and reactions.