To draw the Lewis structure for ethylene (C2H4), we start by determining the total number of valence electrons in the molecule.
Carbon has 4 valence electrons, and hydrogen has 1. Since there are two carbon atoms and four hydrogen atoms, we can calculate the total as follows:
- Carbon: 2 x 4 = 8 valence electrons
- Hydrogen: 4 x 1 = 4 valence electrons
This gives us a total of 8 + 4 = 12 valence electrons to work with.
Now we can start sketching the structure. Ethylene consists of two carbon atoms double-bonded to each other with each carbon atom also bonded to two hydrogen atoms. Therefore, the Lewis structure looks like this:
C = C | | H H
In this representation, the double line (=) between the carbon atoms indicates a double bond, which consists of two shared pairs of electrons. Each carbon is also bonded to two hydrogen atoms. This accounts for all 12 valence electrons:
- 2 electrons from the double bond between the carbon atoms
- 4 electrons from the bonds between each carbon and the four hydrogen atoms (2 electrons per bond)
This structure effectively represents the electron sharing in ethylene, making it a key molecular building block in the plastics industry.