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ScienceQuest

Ethylene (C₂H₄) Lewis structure

12 valence electrons, trigonal planar

C C H H H H
C₂H₄ as the Lewis Structure Generator draws it: lone pairs as dots.

Build C₂H₄ step by step in the Lewis Structure Generator

What is the Lewis structure of C₂H₄?

Ethylene, C₂H₄, has 12 valence electrons. The two C atoms bond to each other, and the molecule has one C=C double bond and four C−H single bonds. It carries no lone pairs. Every formal charge is zero. Each C is AX₃: trigonal planar, with an ideal bond angle of 120°, and the molecule is nonpolar.

Valence electrons in C₂H₄

Element Group Valence electrons Atoms Electrons
Carbon 14 4 2 8
Hydrogen 1 1 4 4
Total 12

In one line: 2 × 4 + 4 × 1 = 12. Each atom brings the valence electrons its group gives it.

How to draw the C₂H₄ Lewis structure

  1. Count the valence electrons. Valence electrons: each C 4 and each H 1. 2 × 4 + 4 × 1 = 12.
  2. Bond the two central atoms. C appears twice, so the two C atoms bond to each other and share the H atoms evenly between them.
  3. Join the atoms with single bonds. Five single bonds use 10 electrons, leaving 12 − 10 = 2.
  4. Complete the outer atoms. Every outer atom is H, and its one bond already gives it the two electrons it holds. 2 remain.
  5. Put the rest on the central atom. The 2 left go on the central atoms as one lone pair on one C, and one C now has 8 electrons round it and the other 6.
  6. Make multiple bonds where needed. One C has only 6 electrons, so one lone pair moves into the bonds, making a C=C bond, and both C now have 8.

Lone pairs and formal charges in C₂H₄

Atom Number Bonds Lone pairs Electrons round it Formal charge, V − N − B/2
C (central) 2 one double bond and two single bonds 0 8 4 − 0 − 4 = 0
H 4 one single bond 0 2 1 − 0 − 1 = 0

V is the atom’s valence electrons, N its nonbonding electrons and B its bonding electrons. The formal charges add up to 0, the molecule’s overall charge.

Shape and polarity of C₂H₄

Central atoms each C
VSEPR class AX₃
Electron geometry trigonal planar
Molecular geometry trigonal planar
Ideal bond angle 120°
Polarity, an estimate nonpolar

The two halves are identical and point opposite ways, so their bond dipoles cancel.

Each C has three σ bonds and no lone pairs, three electron domains in all, so its electron geometry is trigonal planar. With no lone pairs, the molecular geometry is the same.

The VSEPR Molecular Geometry viewer turns the AX₃ shape in 3D, lone pairs included.

Work with C₂H₄