To draw the Lewis structure for ethylene (C2H4), we first need to determine the total number of valence electrons. Carbon has 4 valence electrons, and there are two carbon atoms, giving us a total of 8 electrons. Hydrogen has 1 valence electron, and with four hydrogen atoms, we get an additional 4 electrons. Therefore, the total number of valence electrons in C2H4 is 12.
Now, we can start drawing the structure. We place the two carbon atoms in the center and connect them with a double bond to fulfill the octet rule more effectively. Each carbon will then bond to two hydrogen atoms. The Lewis structure looks like this:
C = C | | H H
In this structure, each carbon atom is surrounded by four electrons (two from the double bond and two from the single bonds with hydrogen), satisfying the octet rule.
The molecular geometry of C2H4 can be described as planar, specifically adopting a trigonal planar shape around each carbon atom due to the double bond and the two single bonds, resulting in bond angles of approximately 120 degrees.
Regarding polarity, ethylene is considered a nonpolar molecule. Although there are polar C-H bonds, the symmetrical arrangement of the molecule means that the dipoles cancel out, resulting in no overall dipole moment. Thus, C2H4 is nonpolar.