Lab Partner: Molecular Modeling – Recitation Submission build each molecule below using the molecular modeling sets. Then, complete the following tables. Use lines and wedges to represent 3-D structures as appropriate (45 points/3 points per row) Formula Complete Lewis Structure Number of Electronic Electronic Domains onGeometry Central Atom Molecular Geometry 3. Dimensional Structure Using Line/Wedge/Dash (including lone pairs) CHE Formula Complete Lewis Structure Number of Electronic Domains on Central Atom Electronic Geometry Molecular Geometry 3-Dimensional Structure Using Line/Wedge/Dash (including lone pairs) BF Formula Complete Lewis Structure Number of Electronic Domains on Central Atom Electronic Geometry Molecular Geometry 3-Dimensional Structure Using Line/Wedge/Dash (including lone pairs) Efavirenz (sold as Sustiva) is an anti-retroviral medication prescribed to treat HIV infection. Complete the boxes by supplying the relevant information in the structure of efavirenz below. (16 points total / 2 points per answer) bond angle bond angle bond angle Ha/ — -H HU bond angle Efavirenz (SustivaTM) Utilize your knowledge of Valence Shell Electron Pair Repulsion (VSEPR) Theory Electron geometry of carbon indicated by *** Electronic geometry of carbon indicated by “@” Molecular geometry at oxygen indicated by “3” Molecular geometry at nitrogen indicated by “S” Answer the following questions. You may utilize your observations of Phet simulations AND/OR fundamental principles of VSEPR theory.
The correct answer and explanation is:
For the molecular modeling and VSEPR-based questions, here is an outline of how you can approach the problem, followed by the explanations:
1. BF₃ (Boron Trifluoride):
- Formula: BF₃
- Complete Lewis Structure: The central atom is boron (B), which is bonded to three fluorine (F) atoms, each with a lone pair of electrons. Boron in this structure does not complete the octet (it has 6 electrons in its valence shell).
- Number of Electronic Domains on Central Atom: 3 (one for each bond to fluorine).
- Electronic Geometry: Trigonal Planar (the regions of electron density around boron are arranged symmetrically in a plane).
- Molecular Geometry: Trigonal Planar (since there are no lone pairs on the central atom, the molecular shape matches the electronic geometry).
- 3-Dimensional Structure Using Line/Wedge/Dash: The molecule will appear as a planar triangle with all bonds to fluorine in the same plane.
Explanation: The central boron atom in BF₃ has 3 regions of electron density (one for each B-F bond). According to VSEPR theory, three electron domains arrange themselves in a trigonal planar geometry, meaning the bond angles between fluorine atoms are 120°. This shape minimizes repulsions between bonding pairs.
2. Efavirenz (Sustiva):
Efavirenz is an anti-retroviral medication with a complex structure. Let’s break down the bond angles and molecular geometries as described:
- Bond Angle between Ha and H: This is likely referring to the bond angle between two hydrogen atoms that are attached to the same carbon atom. Given the sp² hybridization of carbon in a double bond context (C=C), the bond angle would typically be around 120°, indicating a trigonal planar structure at that carbon.
- Bond Angle between H and HU: This likely refers to a bond involving a carbon-hydrogen bond in an sp³ hybridized region. The bond angle here would be close to 109.5° for a tetrahedral arrangement, which is typical for single bonds to hydrogen.
- Bond Angle between Ha and HU: Again, this could involve different carbon centers with different hybridization, so the angles would vary. Expect around 120° for sp² hybridized carbons (planar) or 109.5° for sp³ hybridized carbons (tetrahedral).
Electron Geometry of Carbon (indicated by “*”):** In the context of sp² hybridized carbons (double-bonded or part of aromatic rings), the electron geometry will be trigonal planar.
Molecular Geometry at Oxygen (indicated by “3”): If the oxygen atom is part of an ether or carbonyl group, its electron geometry would be bent (angular), resulting in an approximate bond angle of 104.5°.
Molecular Geometry at Nitrogen (indicated by “S”): Nitrogen, often in a sp³ hybridized state in organic molecules, typically adopts a pyramidal shape, with a bond angle near 107°.
Key Concepts for VSEPR:
- Electron Geometry refers to the arrangement of all electron domains (bonding and lone pairs) around the central atom.
- Molecular Geometry is the arrangement of the atoms around the central atom, considering only the bonds (ignoring lone pairs).
- Bond Angles are predicted based on the electron geometry and can be adjusted depending on the presence of lone pairs (which cause slight deviations from ideal angles).
For the efavirenz molecule:
- The presence of multiple carbon atoms, nitrogen, and oxygen suggests a more complex structure.
- The bond angles and geometry at different atoms will be influenced by their hybridization and the types of bonds formed (single, double, or aromatic).
Final Answer with 300-Word Explanation:
The molecular structure of efavirenz consists of aromatic rings and other functional groups, with each atom’s geometry determined by its hybridization and electron domain count. The bond angles in efavirenz would follow the general trends predicted by VSEPR theory, with carbon atoms in sp² hybridization (in aromatic rings or double bonds) forming trigonal planar structures, and sp³ hybridized carbon atoms (with single bonds to hydrogen) adopting tetrahedral geometries. The oxygen atom likely forms a bent geometry due to its two bonding pairs and lone pair of electrons, while the nitrogen atom is pyramidal due to its sp³ hybridization. The specific bond angles depend on these geometries, with values around 120° for trigonal planar carbons, 109.5° for tetrahedral carbons, and approximately 104.5° for oxygen.