C2H4 Lewis Structure
The Lewis dot structure of ethene (C2H4): a carbon-carbon double bond, 4 C-H single bonds, and a flat, trigonal-planar shape at each carbon.
How to draw the Lewis structure of C2H4
- Count valence electrons: 2 carbons × 4 + 4 hydrogens × 1 = 12 electrons.
- Put the 2 carbons in the centre, bonded to each other, and connect each carbon to 2 hydrogens with single bonds.
- That uses 5 bonds (10 electrons) so far, but each carbon only has 3 bonds — not yet a full 4. Add a second bond between the two carbons, making it a double bond, using the remaining 2 electrons.
- Check: each carbon now has 4 bonds (1 double bond + 2 single bonds to H) and each hydrogen has 1 bond — no lone pairs needed anywhere.
Worked example: why it's flat
Each carbon in C2H4 has exactly 3 electron groups around it: the C=C double bond (counted as one group) and 2 C–H single bonds. Three electron groups spread out as far apart as possible in a flat triangle, called trigonal planar, with roughly 120° angles between them — which is why the whole molecule, all 6 atoms, lies in a single plane.
Build C2H4 and other molecules atom by atom, and see the double bond and flat shape in 3D, in the Molecule Builder below.
Frequently asked questions
Why does C2H4 have a double bond between the carbons?
Each carbon has 4 valence electrons and forms 4 bonds total. With 2 single bonds to hydrogen on each carbon already using 2 of those 4, the remaining bond between the carbons must be a double bond so both carbons reach 4 bonds.
Is C2H4 flat?
Yes. Each carbon has 3 electron groups (the double bond counts as one group, plus 2 C–H bonds), which arrange in a flat triangle (trigonal planar), so the whole 6-atom molecule lies in one plane.
How many total valence electrons does C2H4 have?
12: each carbon contributes 4 (4 × 2 = 8) and each hydrogen contributes 1 (1 × 4 = 4), for 8 + 4 = 12.
What are the H-C-H and H-C-C bond angles in C2H4?
About 120°, since each carbon’s 3 electron groups spread out evenly in a flat trigonal planar arrangement.
