Lewis Structure of Diatomic Molecules Double and Triple Bonds

General Chemistry • Chemical Bonds

Written by STEM Calculators Team Published December 1, 2025 Updated April 21, 2026

Lewis Structures of Diatomic Molecules – Double and Triple Bonds

Build Lewis structures for common diatomic species with double and triple bonds. This calculator counts valence electrons, separates bonding and nonbonding electrons, shows lone-pair placement, identifies bond order, and explains the σ and π parts of the bond.

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These examples are simple diatomic species whose main Lewis structure has one multiple bond along the internuclear axis.

Teaching focus

The chemistry stays the same in every mode. This option changes the visual emphasis and annotations.

For this topic, the key bookkeeping rule is: total valence electrons = contribution from atom 1 + contribution from atom 2 ± charge adjustment. A double bond contains 4 bonding electrons and a triple bond contains 6 bonding electrons.

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Lewis structure diagram

Bond anatomy and electron bookkeeping

Batch results

#	Species	Total valence	Bond order	Nonbonding e⁻	Formal charges	Charge

Click a row to inspect that molecule or ion in the diagrams and step-by-step solution.

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Lewis structures of diatomic molecules with double and triple bonds

For a diatomic molecule or ion, the Lewis structure shows the two atoms, the multiple bond between them, and any lone pairs. We still:

Count the total number of valence electrons (including charge for ions).
Place electrons in a bonding region between the atoms to form a single, double, or triple bond.
Distribute remaining electrons as lone pairs so that each atom reaches an octet whenever possible.

\text{Bond order} = \begin{cases} 1 & \text{single bond} \\ 2 & \text{double bond (one }\sigma\text{ + one }\pi\text{)} \\ 3 & \text{triple bond (one }\sigma\text{ + two }\pi\text{)} \end{cases}

In this set:

\(\mathrm{O_2}\) has an \(\mathrm{O=O}\) double bond and two lone pairs on each oxygen.
\(\mathrm{N_2}\) has an \(\mathrm{N{\equiv}N}\) triple bond and one lone pair on each nitrogen.
\(\mathrm{CO}\), \(\mathrm{CN^-}\), and \(\mathrm{NO^+}\) all have triple bonds (\(\text{bond order} = 3\)) plus lone pairs and formal charges chosen so that the total number of valence electrons matches the neutral molecule or ion.

Later, the same Lewis structures will be used to build molecular orbital and \(\sigma / \pi\) bonding diagrams: each bonding pair becomes a \(\sigma\) or \(\pi\) interaction between atomic orbitals.

Frequently Asked Questions

How do you find the total valence electrons for a diatomic ion like CN- or NO+?

Add the valence electrons from both atoms, then adjust for charge. A negative charge adds electrons, and a positive charge removes electrons (total valence electrons = sum of atomic valence electrons - ionic charge).

What is bond order for a diatomic Lewis structure?

Bond order is the number of shared electron pairs between the two atoms in the Lewis structure. A double bond has bond order 2, and a triple bond has bond order 3.

How many sigma and pi bonds are in a double bond or triple bond?

A double bond contains 1 sigma bond and 1 pi bond. A triple bond contains 1 sigma bond and 2 pi bonds.

Why do multiple bonds appear in some diatomic molecules like O2 and N2?

Multiple bonds form when a single bond would not satisfy typical electron-count goals (like reaching an octet) or would lead to unfavorable electron placement. Sharing more than one pair of electrons can give each atom a more stable valence electron arrangement.

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Feb 20, 2026 Published

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O2 Lewis Dot Structure (Oxygen Molecule)
General Chemistry Chemical Bonds Lewis Structure of Diatomic Molecules Double and Triple Bonds

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