Lewis Dot Structure Generator With Examples
Type a molecule and generate a clean, textbook-style Lewis dot structure in seconds, or study the five reference structures and the rules behind them below.
Five correct examples
Water, carbon dioxide, methane, ammonia, and oxygen — every bond order and lone pair drawn correctly.
The rules, condensed
Valence electrons, the octet rule, and lone pairs explained in three short cards.
Generate your own
Describe any small molecule in words and get its Lewis structure to check against.
Lewis dot structures
Lewis Dot Structures: Five Worked Examples
The diagram below shows the Lewis structures of five molecules every chemistry course starts with. Each structure is listed beneath the figure with its bonds and lone pairs, so you can check any drawing of your own against them.
- H2O — water
- Oxygen sits in the center with two single bonds to hydrogen and two lone pairs on the oxygen. The two lone pairs bend the molecule into its familiar V shape.
- CO2 — carbon dioxide
- Carbon in the center with a double bond to each oxygen; each oxygen carries two lone pairs. Sixteen valence electrons in total, all accounted for.
- CH4 — methane
- Carbon bonded to four hydrogens by single bonds, with no lone pairs anywhere. The textbook example of a full octet with single bonds only.
- NH3 — ammonia
- Nitrogen in the center with three single bonds to hydrogen and one lone pair. The lone pair pushes the bonds into a pyramid shape.
- O2 — oxygen gas
- Two oxygens joined by a double bond, each with two lone pairs. The double bond is what the octet rule demands for both atoms.
The three rules
The Rules Behind Every Structure
Every Lewis structure on this page — and every one you will draw — follows the same three rules.
- Count valence electrons
- Add up the valence electrons from every atom: H contributes 1, C contributes 4, N contributes 5, O contributes 6. The total never changes while you draw.
- The octet rule
- Every C, N, and O atom wants eight electrons around it — shared pairs in bonds plus its own lone pairs. Hydrogen is the common exception: it is full with two.
- Lone pairs vs bonding pairs
- A bonding pair sits between two atoms in a bond; a lone pair belongs to one atom only. Two dots in the wrong place change the whole structure.
Quick reference
Lewis Structure Cheat Sheet
The five molecules above in one table — memorize the electron counts and this table answers most worksheet questions.
| Molecule | Valence electrons | Bonds | Lone pairs (central atom) |
|---|---|---|---|
| H2O | 8 | 2 single | 2 |
| CO2 | 16 | 2 double | 0 |
| CH4 | 8 | 4 single | 0 |
| NH3 | 8 | 3 single | 1 |
| O2 | 12 | 1 double | 2 |
How it works
Generate your own Lewis structures
- Step 1
Name the molecule
Type the formula or describe the atoms — water, carbon dioxide, or any small molecule.
- Step 2
Generate the structure
The generator places the atoms, bonds, and lone pairs in clean textbook style.
- Step 3
Check and export
Count the electrons against the octet rule, ask for corrections, then export.
FAQ
Lewis structure questions
What is a Lewis dot structure?+
A Lewis dot structure shows how the valence electrons of a molecule are arranged: atoms written as element symbols, bonds drawn as lines, and lone pairs drawn as pairs of dots. It is the standard first picture of bonding in introductory chemistry.
How do I draw a Lewis dot structure?+
Count the total valence electrons, place the least electronegative atom (never hydrogen) in the center, connect the atoms with single bonds, distribute the remaining electrons as lone pairs to complete octets, and form double or triple bonds where octets fall short. Our How to Draw Lewis Dot Structures tutorial walks through all five steps with examples.
What do the dots mean in a Lewis structure?+
Each dot is one valence electron. Dots drawn in pairs on a single atom are lone pairs; a pair shared between two atoms forms one covalent bond, drawn as a line.
What is the octet rule?+
Carbon, nitrogen, and oxygen are stable with eight valence electrons — bonds plus lone pairs. Hydrogen is the common exception, full with just two. Elements in the third row and beyond can also hold more than eight.
Why does O2 have a double bond?+
With twelve valence electrons, two single-bonded oxygens would leave each atom with only six electrons. Sharing a second pair as a double bond gives each oxygen a full octet — the double bond plus two lone pairs.
Can I generate Lewis structures for my own molecules?+
Yes. With AcaDraw you name the molecule and the generator draws its Lewis structure in textbook style, which you can refine and export. The free plan is enough to try it; free-plan exports include a watermark.
Method and references
How this page was prepared
The structures and the one-line explanations follow standard introductory chemistry references, including OpenStax Chemistry 2e and LibreTexts Chemistry. The figure is a product-generated teaching draft; it has not been independently peer-reviewed, so check anything critical against your course materials.
Last reviewed: 2026-10-07
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