C2H4 Skeletal Structure and Lewis Structure Explained

If you are trying to draw the c2h4 skeletal structure, the key idea is simple: ethene (also called ethylene) has two carbon atoms joined by a double bond, and each carbon carries two hydrogen atoms. Every atom reaches a full outer shell, and the molecule is flat. This article shows how to build the Lewis structure step by step, how it relates to the skeletal drawing, what the geometry looks like and common mistakes to avoid. It suits chemistry students at school or first-year university level.

Counting valence electrons for C2H4

Start by counting. Carbon is in group 14 and has 4 valence electrons; hydrogen has 1. So two carbons give 8, four hydrogens give 4, and the total is 12 electrons, or 6 pairs. This count is the foundation for any Lewis diagram, and it also acts as a check at the end.

Atom	Number	Valence electrons each	Total
Carbon	2	4	8
Hydrogen	4	1	4
Total			12

Drawing the Lewis structure step by step

1. Choose the central atoms. Hydrogen can only form one bond, so the two carbons form the backbone.
2. Join the atoms with single bonds. Connect C to C, then add two H atoms to each carbon. That uses 5 bonds, or 10 electrons.
3. Place the remaining electrons. You have 2 left. Hydrogen is already full, so add them to the carbons.
4. Check octets. Each carbon has only 3 bonds (6 electrons), which is incomplete.
5. Form a double bond. Move the lone pair into the space between the carbons so they share two pairs.
6. Verify. Each carbon now has 4 bonds (8 electrons), and each hydrogen has 2. Total electrons used: 12.

The finished Lewis structure is H2C=CH2, with no lone pairs on any atom.

What the c2h4 skeletal structure looks like

A skeletal formula, also known as a line-angle drawing, is a simplified way chemists draw organic molecules. Carbon atoms are not labelled; they appear at the ends and corners of lines. Hydrogens attached to carbon are not shown, but are assumed to fill each carbon’s four bonds. For ethene, the skeletal structure is simply a double line, and everyone reading it understands that each end carbon has two hydrogens. You can compare conventions on the Wikipedia page on skeletal formulae.

Lewis versus skeletal: quick comparison

• Lewis structure: shows every atom and valence electron pair.
• Skeletal structure: hides carbon and hydrogen labels for speed.
• Condensed formula: CH2=CH2 is a text version.

Shape and bond angles

Each carbon has three regions of electron density: two C-H single bonds and one C=C double bond. According to VSEPR theory, that gives a trigonal planar arrangement with ideal angles of 120 degrees. In practice, the H-C-H angle is a bit smaller, around 117 degrees. All six atoms lie in the same plane. The planar shape comes from the way the double bond forms.

Sigma and pi bonds

The double bond is made of one sigma bond and one pi bond. Each carbon uses sp2 hybrid orbitals to form three sigma bonds, and the leftover p orbitals overlap sideways to form the pi bond. This pi bond stops rotation around the C=C axis and makes ethene more reactive than ethane. For a deeper background, see the Wikipedia article on ethylene.

Polarity and properties

Ethene is nonpolar. The molecule is symmetrical, and the small differences in electronegativity between carbon and hydrogen cancel out. It is a gas at room temperature, slightly soluble in water and widely used to make plastics such as polyethylene. It is also a plant hormone that helps fruit ripen.

Common mistakes

• Forgetting to count electrons first, then ending up with a wrong number of bonds.
• Leaving carbons with only three bonds.
• Adding lone pairs on carbon that do not belong.
• Drawing a linear shape instead of trigonal planar.
• Putting hydrogen in the middle of the structure.

Practice and revision tips

Try the same method for C2H6 and C2H2 and note how the bonding changes from single to triple. If you like maths-style practice too, our notes on the semicircle formula and the four quadrants on a graph follow a similar step-by-step layout.

Worked example: checking your own drawing

Once you have sketched the c2h4 skeletal structure or the full Lewis diagram, run through a short audit. It takes less than a minute and catches nearly every error.

1. Count the bonds on each carbon. Each must total four, counting the double bond as two.
2. Count the bonds on each hydrogen. Each must have exactly one.
3. Add up the electrons: 5 shared pairs from single bonds plus the extra pair in the double bond gives 6 pairs, or 12 electrons.
4. Look for lone pairs. There should be none.
5. Compare the geometry with your picture: flat, with all angles near 120 degrees.

Formal charge check

Formal charge equals valence electrons minus non-bonding electrons minus half the bonding electrons. For each carbon: 4 – 0 – 4 = 0. For each hydrogen: 1 – 0 – 1 = 0. Every atom has zero formal charge, which tells you this is the most stable and correct arrangement.

How ethene compares with related molecules

Molecule	C-C bond	Carbon hybridisation	Shape at carbon
Ethane, C2H6	Single	sp3	Tetrahedral
Ethene, C2H4	Double	sp2	Trigonal planar
Ethyne, C2H2	Triple	sp	Linear

Frequently asked questions

Conclusion

Once you know the electron count, building the Lewis diagram for ethene is quick, and the c2h4 skeletal structure is just a double line. Remember the planar 120 degree geometry, the sigma-plus-pi bond, and always check that every carbon has four bonds.