Ethylene, C2 H4, and tetrafluoroethylene, C2 F4, are used to make the polymers polyethylene and

step 1 Okay, so for part A of this question, we're just going to draw the lubeist structures of C2H4 an

Ethylene, C2 H4, and tetrafluoroethylene, C2 F4, are used...

Ethylene, $\mathrm{C}_{2} \mathrm{H}_{4},$ and tetrafluoroethylene, $\mathrm{C}_{2} \mathrm{~F}_{4},$ are used to make the polymers polyethylene and polytetrafluoroethylene (Teflon), respectively. (a) Draw the Lewis structures for $\mathrm{C}_{2} \mathrm{H}_{4}$ and $\mathrm{C}_{2} \mathrm{~F}_{4},$ and give the ideal $\mathrm{H}-\mathrm{C}-\mathrm{H}$ and $\mathrm{F}-\mathrm{C}-\mathrm{F}$ bond angles. (b) The actual $\mathrm{H}-\mathrm{C}-\mathrm{H}$ and $\mathrm{F}-\mathrm{C}-\mathrm{F}$ bond angles are $117.4^{\circ}$ and $112.4^{\circ},$ respectively. Explain these deviations.

Ethylene, $\mathrm{C}_{2} \mathrm{H}_{4},$ and tetrafluoroethylene, $\mathrm{C}_{2} \mathrm{~F}_{4},$ are used to make the polymers polyethylene and polytetrafluoroethylene (Teflon), respectively.
(a) Draw the Lewis structures for $\mathrm{C}_{2} \mathrm{H}_{4}$ and $\mathrm{C}_{2} \mathrm{~F}_{4},$ and give the ideal $\mathrm{H}-\mathrm{C}-\mathrm{H}$ and $\mathrm{F}-\mathrm{C}-\mathrm{F}$ bond angles.
(b) The actual $\mathrm{H}-\mathrm{C}-\mathrm{H}$ and $\mathrm{F}-\mathrm{C}-\mathrm{F}$ bond angles are $117.4^{\circ}$ and $112.4^{\circ},$ respectively. Explain these deviations.

Key Concepts

Lewis Structure

The Lewis structure is a diagrammatic method used to represent the bonding between atoms in a molecule as well as any lone pairs of electrons that might exist. In molecules like ethylene and tetrafluoroethylene, these structures help illustrate the double bonds between carbon atoms and the connections between carbon and hydrogen or fluorine atoms. This method is crucial for predicting molecular geometry and understanding bonding interactions.

Hybridization

Hybridization refers to the mixing of atomic orbitals to form new hybrid orbitals that are more suitable for the pairing of electrons to form chemical bonds. In both ethylene and tetrafluoroethylene, the carbon atoms are sp2 hybridized, which leads to a trigonal planar arrangement around each carbon atom. This concept explains why the ideal bond angles are around 120° in these molecules.

Molecular Geometry

Molecular geometry describes the three?dimensional arrangement of atoms within a molecule. In the case of ethylene and tetrafluoroethylene, the sp2 hybridization of carbon produces a planar structure with an idealized 120° bond angle around the carbon atoms. Understanding molecular geometry is essential for explaining the spatial arrangement and relative positions of the bonds in a molecule.

Bond Angle Deviations

Although sp2 hybridized molecules ideally have bond angles of 120°, experimental measurements often show slight deviations. In ethylene and tetrafluoroethylene, the observed H–C–H and F–C–F bond angles are less than 120° due to factors such as electron–electron repulsion and substituent effects. The different electronegativities and the presence of lone pairs (especially in the case with fluorine atoms) can alter the distribution of electron density around the central atom, leading to a contraction of the bond angles compared to the idealized geometry.

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