Lewis structure view
Short answer: Click the graduation cap Teaching button and switch on Lewis structure. MolDraw shows every atom symbol, every hydrogen and the lone pairs as dots. Only the view changes. Your drawing stays the same, and you switch back the same way.
The Lewis structure view turns any skeletal drawing into a full Lewis structure. It is a display option. You draw in the normal way, and MolDraw adds the parts a Lewis structure needs.
- Draw your structure, or paste a SMILES.
- Click the Teaching button (graduation cap) in the top bar.
- Switch on Lewis structure.
- Switch it off to go back to the skeletal formula.
In Settings, General, Teaching, the same option is Structure display, with Skeletal formula and Lewis structure. The default is Skeletal formula.
What it shows#
| Part | In the Lewis view |
|---|---|
| Carbon atoms | Every atom shows its symbol, C included |
| Hydrogens | Each hydrogen is drawn as an H with its own bond |
| Lone pairs | Non bonding pairs show as dots on B, C, N, O, F, Si, P, S, Cl, Br and I |
| Your own lone pairs | Pairs you placed by hand stay as you drew them |
| Aromatic rings | Drawn with alternating double bonds instead of a circle |
| Labels like Ph or COOH | Stay as labels |
The extra hydrogens and dots are not real atoms in your file. You can still select, move and edit the structure as usual. Undo works the same.
Exports#
Downloads and copied images use the view on screen. Turn on Lewis structure before you download a PNG or SVG to get a Lewis figure. Turn it off to export the skeletal formula. File formats like SMILES and MOL do not change. See Download and file formats.
With other teaching options#
- Show errors: a drawn lone pair that does not fit the charge gets an amber dot. See Show errors.
- Free sketch mode: with No automatic hydrogens on, the Lewis view shows only the atoms and pairs you drew. Students then add every H and pair themselves. See Free sketch mode.
- Ball and stick: the Lewis view does not apply to the ball and stick look.
Tips#
- Draw a skeletal structure, then switch views to show students how the two forms match.
- Use Clean up first if the hydrogens crowd each other.
- For single dots, charges and the line style for pairs, see Lone pairs, radicals and charges.
Common problems#
| Problem | Fix |
|---|---|
| No lone pairs on an atom | Dots appear only on main group atoms with a known electron count. Metals and labels get none. |
| A charge looks wrong in the view | The view follows the charge you drew. Fix the charge with the plus and minus tools. |
| The view did not change | Check that the structure is not in the ball and stick look. |
The Lewis structure generator is a separate free tool that builds Lewis structures from a formula.
Questions and answers
How do I show lone pairs on all atoms in MolDraw?
Switch on Lewis structure in the graduation cap Teaching menu. MolDraw draws the lone pairs as dots on every main group atom.
Does the Lewis view change my structure?
No. It is display only. The extra hydrogens and dots are not saved as atoms, and SMILES or MOL output stays the same.
Can I export a Lewis structure image?
Yes. Switch on Lewis structure, then download a PNG, SVG or PDF. The image shows the Lewis view.
How do I show all hydrogens in a structure?
Switch on Lewis structure in the Teaching menu. Every hydrogen is drawn with its own bond.
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