Lewis Structure Generator
Random Lewis structure generator practice

Lewis Structure Practice Problems

Choose a random molecule, draw its Lewis structure on paper, then reveal a hint or open the detailed answer guide. The set includes easy octet examples, multiple bonds, resonance and octet-rule exceptions.

Easy
H₂O
Water · Focus: lone pairs and bent geometry
Open generatorView answer guide
Hint

Count 8 valence electrons. Oxygen is central and has two lone pairs after forming two O–H bonds.

How to use the practice generator

  1. Write the total valence-electron count.
    Adjust for any ionic charge before drawing.
  2. Sketch the atom connectivity.
    Choose a central atom and connect terminal atoms with single bonds.
  3. Add lone pairs and multiple bonds.
    Complete terminal octets, then repair the central atom if needed.
  4. Calculate formal charges.
    Check that the charges add to the overall charge and compare reasonable alternatives.
  5. Predict the geometry.
    Count electron domains around the central atom and apply VSEPR.
  6. Open the answer guide.
    Compare your result only after completing your own drawing.

Practice set coverage

Foundation

  • H2O
  • CO2
  • NH3
  • CH4
  • CCl4

Multiple bonds and resonance

  • C2H4
  • O3
  • SO2
  • HNO3

Octet exceptions

  • BF3
  • PCl5
  • SF6

Scoring checklist

CheckPoint
Correct total valence electrons1
Reasonable atom connectivity1
All electrons shown1
Octets, duets or documented exception handled1
Formal charges and resonance shown where needed1
Geometry identified correctly1

Practice set reviewed July 15, 2026.