Lewis Structure Guide

How to draw Lewis structures.

Use this checklist before opening a molecule page: count valence electrons, choose a skeleton, place lone pairs, form multiple bonds, and check formal charges.

Formula Search

Find a Lewis structure

Search by formula or English name. Examples: CO2, carbon dioxide, water, nitrate ion.
CO2H2OCH4NH3SO2NO3-CO32-HCN

Drawing Checklist

  1. Count total valence electrons. Add electrons for negative charge and subtract electrons for positive charge.
  2. Choose a likely central atom. Hydrogen is never central, and less electronegative atoms are often central.
  3. Connect atoms with single bonds.
  4. Fill terminal atom octets first, except hydrogen, which only needs two electrons.
  5. Move lone pairs into double or triple bonds if the central atom lacks an octet.
  6. Check formal charges and resonance forms.

FAQ

How do you draw a Lewis dot structure?

Count total valence electrons, draw a skeleton, place lone pairs on terminal atoms, add remaining electrons to the central atom, then form double or triple bonds if an octet is incomplete.

What should you check after drawing a Lewis structure?

Check octets, hydrogen duets, total electron count, formal charges, resonance forms, molecular geometry, and polarity.

Are Lewis structures and Lewis dot structures the same?

In most classroom searches, the terms refer to the same electron-dot drawing. Lines show shared electron pairs, and dots show lone pairs.