Considering the C2Cl4 molecule: a) Draw the box and arrow configuration and the Lewis structure of C2Cl4. b) Draw the overlap of the orbitals (Hybridization diagram) of the C2Cl4 molecule. c) Indicate the quantity and type of bond (σ or π ) that results. d) Indicate the approximate value of the angle Cl-C-Cl. e) Explain whether the C2Cl4 molecule will tend to orient or not under the influence of an electric field
The correct Answer and Explanation is:
Certainly! Let’s walk through each part of the question for the C₂Cl₄ (tetrachloroethylene) molecule.
a) Box and Arrow Configuration & Lewis Structure
Box and Arrow Configuration:
Each carbon (C) has 4 valence electrons. Each chlorine (Cl) has 7 valence electrons.
- For C (1s² 2s² 2p²) → 4 valence electrons:
C: 1s² | 2s² | 2p: ↑ ↑ (two unpaired in 2p)
Carbon needs to form 4 bonds → it undergoes sp² hybridization.
Lewis Structure:
Cl Cl
\ /
C == C
/ \
Cl Cl
- Each C shares a double bond (C=C), and two single bonds with Cl atoms.
- Each Cl has 3 lone pairs.
b) Hybridization (Orbital Overlap) Diagram
- Each C atom is sp² hybridized:
- Three sp² hybrid orbitals form σ bonds: two with Cl atoms and one with the other carbon.
- One unhybridized p orbital on each carbon forms the π bond in the C=C double bond.
Overlap:
- σ (C–Cl): overlap of C(sp²) – Cl(p)
- σ (C–C): overlap of C(sp²) – C(sp²)
- π (C=C): lateral overlap of unhybridized p orbitals on each C
c) Bond Types and Quantity
- C=C: 1 σ and 1 π bond
- 4 C–Cl bonds: 4 σ bonds
Total Bonds:
- σ bonds: 5 (4 C–Cl + 1 C–C)
- π bonds: 1 (from C=C)
d) Cl–C–Cl Bond Angle
- Since each carbon is sp² hybridized, bond angles are approximately 120°.
- So, ∠Cl–C–Cl ≈ 120°
e) Electric Field Orientation (Polarity)
C₂Cl₄ is a nonpolar molecule.
- Despite individual C–Cl bonds being polar, the molecule is symmetric.
- The dipoles cancel due to the tetra-substituted symmetric structure.
Conclusion:
C₂Cl₄ does not orient in an electric field because it has no net dipole moment (nonpolar molecule).
Summary Explanation
Tetrachloroethylene (C₂Cl₄) is a planar, symmetrical molecule featuring a central C=C double bond with each carbon atom also bonded to two chlorine atoms. In drawing the box and arrow configuration, each carbon has four valence electrons, forming bonds via sp² hybridization. Each carbon uses three sp² orbitals to form σ bonds—two with chlorine atoms and one with the other carbon atom. The remaining unhybridized p orbital on each carbon overlaps side-to-side to form a π bond, completing the double bond between the carbon atoms.
The Lewis structure illustrates the connectivity, with a C=C double bond and four single C–Cl bonds. The orbital hybridization diagram confirms the geometry and bonding: 4 σ bonds with chlorine atoms and 1 σ + 1 π bond between carbons.
In terms of bonding, the molecule has 5 σ bonds and 1 π bond. Due to the sp² hybridization, each carbon center forms bond angles of approximately 120°, including the Cl–C–Cl angles.
Although each C–Cl bond is polar, C₂Cl₄ is a nonpolar molecule overall. Its symmetry ensures the dipole moments of the bonds cancel out. Thus, the molecule does not orient in an electric field, unlike polar molecules which align due to net dipole moments.
This combination of bonding, hybridization, and symmetry makes tetrachloroethylene a chemically stable and nonpolar compound, with wide use in industrial applications as a solvent.
