The Lewis structure for ethene (C₂H₄) consists of a central carbon-carbon double bond with single bonds between the carbon atoms and hydrogen atoms. Here’s how to draw the correct Lewis structure for C₂H₄:
Step-by-Step Process:
- Count the Total Number of Valence Electrons:
- Carbon (C) is in group 14, so each carbon atom has 4 valence electrons.
- Hydrogen (H) is in group 1, so each hydrogen atom has 1 valence electron.
- Total valence electrons = (2 carbon × 4) + (4 hydrogen × 1) = 8 valence electrons.
- Place the Carbon Atoms and Form Bonds:
- Carbon atoms will be in the center because they can form multiple bonds.
- Connect the two carbon atoms with a double bond (C=C). A double bond consists of 4 electrons.
- Attach Hydrogen Atoms:
- Each carbon needs to form 4 bonds to satisfy the octet rule (except for hydrogen, which follows the duet rule).
- Since each carbon atom is already involved in a double bond with the other carbon, it will form single bonds with 2 hydrogen atoms.
- Distribute the Remaining Electrons:
- After forming the bonds, you have used 8 electrons (4 electrons for the C=C bond and 4 for the C-H bonds).
- All valence electrons have been accounted for.
Final Structure:
- The carbon-carbon bond is a double bond (C=C).
- Each carbon is single-bonded to two hydrogen atoms.
- All atoms have their valence shells filled: carbon has 8 electrons, and hydrogen has 2 electrons.
The correct Lewis structure of C₂H₄ is:
H₂C=CH₂
Where:
- The “=” symbol represents the double bond between the two carbon atoms.
- The lines between carbon and hydrogen represent single bonds.
This structure satisfies the octet rule for carbon and the duet rule for hydrogen.