Lewis Structure Examples in Chemistry

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Lewis Structure.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

A diagram showing atoms, bonds, and lone pairs of electrons in a molecule, following the octet rule.

A map showing how electrons are arranged and shared between atoms.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Lewis structures show both bonding electron pairs (bonds) and non-bonding lone pairs.

Common stuck point: Don't forget lone pairs—they affect molecular shape and chemical properties.

Worked Examples

Example 1

easy
Draw the Lewis structure for water (\text{H}_2\text{O}).

Solution

  1. 1
    Count total valence electrons: O has 6, each H has 1. Total = 6 + 2(1) = 8.
  2. 2
    Place O as the central atom with single bonds to each H (uses 4 electrons).
  3. 3
    Distribute remaining 4 electrons as 2 lone pairs on oxygen.
  4. 4
    Check: O has 4 bonding + 4 lone pair = 8 electrons (octet satisfied). Each H has 2 electrons (duet satisfied).

Answer

\text{H–O–H with 2 lone pairs on O}
Lewis structures show the arrangement of valence electrons in a molecule. Oxygen's two lone pairs and two bonding pairs create the bent shape of water.

Example 2

medium
Draw the Lewis structure for carbon dioxide (\text{CO}_2).

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

hard
Draw the Lewis structure for the nitrate ion (\text{NO}_3^-). Include formal charges.

Example 2

medium
Draw the Lewis structure for ammonia (\text{NH}_3), and state how many lone pairs are on the nitrogen atom.
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Background Knowledge

These ideas may be useful before you work through the harder examples.

covalent bondoctet rule