Molecule Builder.
Connect atoms. Follow the electrons.
Molecule catalog · 18
Load a complete structure to inspect or edit. This replaces your current workspace.
Neutral molecules
Ions
Choose an atom, then another, to form a bond.
Add your first atom
Drag an atom here or choose one in the palette.
Try oxygen and two hydrogens for water.Your molecule
Formula from your atoms
Positive charge removes electrons; negative charge adds electrons.
Ready to build
Add atoms, then use Connect to join them.
Valid Lewis accounting does not establish physical stability. Lone pairs are placed automatically; this model does not predict molecular geometry or resonance.
How this model counts electrons
Available electrons = sum of atomic valence electrons − total charge. Each bond order uses two electrons. Remaining electrons fill terminal atoms before internal atoms, within a duet for H or an octet for the other elements. Formal charge = valence electrons − nonbonding electrons − bond order sum. Automatic placement shows one drawing; incomplete drawings can place charges differently. Chlorine’s expanded octets and odd-electron chemistry are outside this MVP.
Reference: OpenStax: Lewis structures ↗ · Formal charges ↗