Question

Give an example of a hydrocarbon that, in theory, exhibits each of the following bond angles: \(60^{\circ}, 90^{\circ}, 109.5^{\circ}, 120^{\circ},\) and \(180^{\circ} .\)

Short answer

Examples of hydrocarbons that exhibit the desired bond angles are: - 60° bond angle: cyclopropane (C3H6) - 90° bond angle: None (hydrocarbons do not exhibit this bond angle) - 109.5° bond angle: methane (CH4) - 120° bond angle: ethylene (C2H4) - 180° bond angle: acetylene (C2H2)

Step-by-step solution

60° Bond Angle Example

To find a hydrocarbon with a 60° bond angle, we need to look for molecules with a trigonal planar geometry, where the central atom is connected to three other atoms, and all atoms are in the same plane. An example of a hydrocarbon that exhibits a 60° bond angle is cyclopropane (C3H6), where each carbon atom is connected to two other carbon atoms, forming a triangle. The bond angles between carbon-hydrogen and carbon-carbon bonds in the molecule are approximately 60°.

90° Bond Angle Example

To find a hydrocarbon with a 90° bond angle, we need to look for molecules with a tetrahedral geometry, where the central atom is connected to four other atoms. However, due to the nature of hydrocarbons, it is not possible to find an example of a hydrocarbon with a 90° bond angle, as all hydrocarbons have either smaller or larger bond angles.

109.5° Bond Angle Example

To find a hydrocarbon with a 109.5° bond angle, we need to look for molecules with a tetrahedral geometry, where the central atom is connected to four other atoms. An example of such a hydrocarbon is methane (CH4). The bond angles between carbon and hydrogen in methane are approximately 109.5°.

120° Bond Angle Example

To find a hydrocarbon with a 120° bond angle, we need to look for molecules with a trigonal planar geometry, where the central atom is connected to three other atoms, and all atoms are in the same plane. An example of such a hydrocarbon is ethylene (C2H4). The bond angles between carbon-hydrogen and carbon-carbon bonds in the molecule are approximately 120°.

180° Bond Angle Example

To find a hydrocarbon with a 180° bond angle, we need to look for molecules with a linear geometry, where the central atom is connected to two other atoms, and all atoms are in a straight line. An example of such a hydrocarbon is acetylene (C2H2). The bond angle between the carbon-carbon triple bond and the carbon-hydrogen single bonds in acetylene is 180°.

Key concepts

Cyclopropane

Cyclopropane is an interesting hydrocarbon due to its unique structure, which leads to unusual bond angles. In cyclopropane, the carbon atoms form a triangle, resulting in bond angles of approximately 60 degrees. This is significantly smaller than the typical tetrahedral angle of 109.5 degrees found in many other alkanes like methane.

This strained angle arises due to the molecular geometry forcing the carbon atoms into a triangular shape, deviating from their usual tetrahedral configuration. The tension from this angle creates a significant ring strain because the bonds prefer to exist at "normal" angles, impacting the stability and reactivity of cyclopropane.

Therefore, cyclopropane serves as a classic example in chemistry of ring strain and its effects on molecular stability. This makes it an excellent study subject in understanding molecular geometry and bonding in cyclic compounds.

Methane Geometry

Methane, with the formula CH extsubscript{4}, provides a perfect example of a tetrahedral geometry. In this structure, the central carbon atom forms bonds with four hydrogen atoms. The molecule achieves its stability by arranging these bonds as far apart as possible, resulting in bond angles of 109.5 degrees.

This tetrahedral shape is a common feature in simple hydrocarbons and helps minimize repulsions between bonding electron pairs. As a result, methane adopts a very symmetrical shape, which is essential for its chemical properties and behavior.

• Methane's geometry is not only central to its stability but also a standard model for understanding organic molecules with single bonds.
• Its simplicity makes it a fundamental reference point when studying more complex organic structures.

By understanding methane's geometry, students can better appreciate how molecular shapes influence physical and chemical properties.

Ethylene Planar Structure

Ethylene, with the chemical formula C extsubscript{2}H extsubscript{4}, is an example of a hydrocarbon with a planar geometry. In ethylene, each carbon atom forms a double bond with the other carbon atom, creating a planar trigonal structure around each carbon.

The bond angles in ethylene are approximately 120 degrees. This angle is due to the sp extsuperscript{2} hybridization of each carbon atom, which allows the molecule to maintain planarity. Such a configuration is vital for various chemical reactions, especially those involving polymerization processes.

• The planar structure of ethylene is particularly significant in the formation of polymers, like polyethylene, which is derived from ethylene units.
• Understanding ethylene's molecular shape is essential for comprehending its reactivity and uses in industrial chemistry.

The study of ethylene provides fundamental insights into chemistry that are applicable to countless materials and processes.

Acetylene Linear Structure

Acetylene, known by its formula C extsubscript{2}H extsubscript{2}, is the simplest alkyne and showcases a linear geometry. In acetylene, the two carbon atoms are connected by a triple bond, resulting in a 180-degree bond angle. This linear arrangement is due to the sp hybridization of carbon atoms, a key characteristic of alkynes.

The linear structure means all atoms in acetylene lie on a straight line, which significantly influences its reactivity and how it interacts with other molecules. This geometry is not only intriguing for its simplicity but also for its importance in various chemical applications.

• Acetylene is a crucial starting material in many organic syntheses due to its triple bond, which can be manipulated for various chemical reactions.
• Its linear structure allows it to act as a building block for more complex molecular architectures.

By studying acetylene, students can comprehend the implications of bond types and angles on molecular properties and uses in industry and synthesis.