GeBr4, CBr2H2, SiF4, CCl4, XeCl2, SiH2Br2, CHBr3 -Total number of valence Electrons -The Lewis Structure -The total regions of electrons -Number of bonding regions of electrons, -The shape -And if they are polar or not?
The Correct Answer and Explanation is :
Let’s analyze each compound step by step.
1. GeBr₄
- Valence Electrons: Ge (4) + 4×Br (4×7) = 32.
- Lewis Structure: Ge in the center with 4 single bonds to Br atoms, each Br having 3 lone pairs.
- Total Regions of Electrons: 4 (all bonding pairs).
- Bonding Regions: 4.
- Shape: Tetrahedral.
- Polarity: Nonpolar (symmetrical bond dipoles cancel out).
2. CBr₂H₂
- Valence Electrons: C (4) + 2×Br (2×7) + 2×H (2×1) = 20.
- Lewis Structure: C in the center, single bonds to 2 Br atoms and 2 H atoms.
- Total Regions of Electrons: 4 (all bonding pairs).
- Bonding Regions: 4.
- Shape: Tetrahedral.
- Polarity: Polar (Br creates stronger dipoles compared to H).
3. SiF₄
- Valence Electrons: Si (4) + 4×F (4×7) = 32.
- Lewis Structure: Si in the center with 4 single bonds to F atoms, each F having 3 lone pairs.
- Total Regions of Electrons: 4 (all bonding pairs).
- Bonding Regions: 4.
- Shape: Tetrahedral.
- Polarity: Nonpolar (symmetrical bond dipoles cancel out).
4. CCl₄
- Valence Electrons: C (4) + 4×Cl (4×7) = 32.
- Lewis Structure: C in the center with 4 single bonds to Cl atoms, each Cl having 3 lone pairs.
- Total Regions of Electrons: 4 (all bonding pairs).
- Bonding Regions: 4.
- Shape: Tetrahedral.
- Polarity: Nonpolar (symmetrical bond dipoles cancel out).
5. XeCl₂
- Valence Electrons: Xe (8) + 2×Cl (2×7) = 22.
- Lewis Structure: Xe in the center with 2 single bonds to Cl atoms and 3 lone pairs.
- Total Regions of Electrons: 5 (2 bonding pairs + 3 lone pairs).
- Bonding Regions: 2.
- Shape: Linear.
- Polarity: Nonpolar (symmetrical bond dipoles cancel out).
6. SiH₂Br₂
- Valence Electrons: Si (4) + 2×H (2×1) + 2×Br (2×7) = 20.
- Lewis Structure: Si in the center with single bonds to 2 H atoms and 2 Br atoms.
- Total Regions of Electrons: 4 (all bonding pairs).
- Bonding Regions: 4.
- Shape: Tetrahedral.
- Polarity: Polar (Br creates stronger dipoles compared to H).
7. CHBr₃
- Valence Electrons: C (4) + H (1) + 3×Br (3×7) = 26.
- Lewis Structure: C in the center with single bonds to H and 3 Br atoms.
- Total Regions of Electrons: 4 (all bonding pairs).
- Bonding Regions: 4.
- Shape: Tetrahedral.
- Polarity: Polar (Br creates strong dipoles compared to H).
Explanation (300 words):
The molecular geometry and polarity of a compound depend on the number of valence electrons, bonding regions, lone pairs, and electronegativity. Using the VSEPR (Valence Shell Electron Pair Repulsion) theory, molecules with 4 electron regions around the central atom (like GeBr₄, SiF₄, and CCl₄) form a tetrahedral shape, minimizing electron pair repulsions.
Symmetry plays a key role in polarity. For instance, symmetrical tetrahedrals like GeBr₄ and CCl₄ are nonpolar because bond dipoles cancel. However, molecules with different atoms bonded to the central atom (e.g., CBr₂H₂ or SiH₂Br₂) tend to be polar as dipoles do not cancel due to differing electronegativities.
In linear structures like XeCl₂, the symmetry of bond dipoles (Cl atoms on opposite sides) ensures nonpolarity. Conversely, in molecules like CHBr₃, asymmetry leads to a polar molecule.
Understanding these principles helps predict molecular properties, interactions, and behavior in chemical reactions.