Question

Ethylene, C2H4, and tetrafluoroethylene, C2F4, are used to make the polymers polyethylene and polytetrafluoroethylene (Teflon), respectively. (a) Draw the Lewis structures for C2H4 and C2F4, and give the ideal H-C-H and F-C-F bond anges. (b) The actual H-C-H and F-C-F bond angles are 117.4∘ and 112.4∘ respectively. Explain these deviations.

Answer 1

Explanation:

The Lewis structures can be seen in the Figure below.

The ideal bond angle for both H-C-H and F-C-F is 120° because the have a triangular geometry.

The H-C-H has 117.4° angles due to the repulsion caused by the electrons of the double bond and the electrons of the H-C bond. This repulsion brings closer the H and decreases the angle.

On the other hand, in the F-C-F the same phenomenom happens but given that the F have lone pairs of electrons the repulsion is bigger, the F get closer and the angle is smaller than the H-C-H.