Carbon dioxide Lewis Structure

Carbon Dioxide Lewis Structure: CO₂ Lewis Structure, Linear Geometry, sp Hybridization & Polarity

Carbon dioxide Key Facts

The carbon dioxide Lewis structure is O=C=O, with carbon at the center double-bonded to two oxygens; the molecule is linear, the central carbon carries no lone pairs, the C=O bond angle is 180°, carbon is best described as sp-hybridized, and because the two equal bond dipoles cancel, CO₂ is nonpolar.

Figure 1: Lewis Structure of Carbon dioxide (CO₂)

Chemical Formula	CO₂
CAS Number	124-38-9
Total Valence Electrons	16
Lewis Structure	O=C=O, two C=O double bonds
Electron-Domain Geometry	Linear
Molecular Geometry	Linear
Hybridization Model	sp (central carbon)
O=C=O Bond Angle	180°
Polarity	Nonpolar molecule

PubChem and NIST identify carbon dioxide as CO ₂ with CAS 124-38-9; PubChem lists a molecular weight of approximately 44.009 g/mol. View CAS 124-38-9 dictionary details on Guidechem →

Applications of Carbon dioxide (CAS 124-38-9)

Carbon dioxide is far more than a classroom example of a linear molecule. Industrially, CO₂ is produced at scale as a by-product of ammonia synthesis, fermentation, and fossil-fuel combustion, and it is captured, purified and sold in multiple grades. Its chemical inertness in the absence of strong nucleophiles or reducing agents, together with its low toxicity relative to many industrial gases, makes it valuable across food, energy and materials sectors.

In the chemical industry, CO₂ is a feedstock for urea (via reaction with ammonia), for salicylic acid, and increasingly for polycarbonates and other CO₂-derived polymers. In the food and beverage sector it provides carbonation and inert modified-atmosphere packaging. Supercritical CO₂ is a widely used green solvent for decaffeination, hop extraction and specialty extractions, while solid CO₂ (dry ice) is a common refrigerant and shipping coolant.

Industrial Gas & Fire Suppression Blanketing and inerting of flammable atmospheres, and dense-phase displacement of oxygen in fixed fire-suppression systems.

Supercritical Extraction Supercritical CO₂ as a tunable, low-residue solvent for decaffeination, hops and botanical extraction.

Chemical Feedstock Urea, salicylic acid and emerging polycarbonate/polymer routes that consume captured CO₂.

Procurement Note "Carbon dioxide" spans beverage-grade, food-grade, pharmaceutical, welding and industrial grades, each with strict limits on oil, moisture, odor and impurity profile. When screening suppliers, specify the required grade, purity, dew point and package (cylinder, bulk liquid, or solid), and use CAS 124-38-9 as the primary identifier. Buyers should also confirm whether the gas is virgin or recovered/recaptured CO₂.

Step 1 - Valence Electrons & Central Atom

The first step in drawing the CO₂ Lewis structure is to sum all valence electrons. Carbon is in Group 14 and contributes 4 valence electrons. Each oxygen is in Group 16 and contributes 6 valence electrons.

Valence-electron count

Total valence electrons = 4 from C + 6 from O + 6 from O = 16 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place carbon in the center with the two oxygens on either side: O – C – O. A single bond to each oxygen consumes 4 of the 16 electrons, leaving 12. Distributing those as lone pairs gives each oxygen three lone pairs, but that leaves carbon with only 4 electrons (an incomplete octet) and yields high formal charges.

To satisfy the octet rule and minimize formal charge, convert each single bond into a double bond: O=C=O. Each double bond uses 4 electrons, so two double bonds consume 8 electrons, and the remaining 8 electrons become two lone pairs on each oxygen. Every atom now has a complete octet, and formal charges are zero.

O = C = O

Each oxygen carries two lone pairs (··O=C=O··)

2 double bonds = 4 electron domains around carbon, all bonding

Octet Rule & Formal Charge Minimization With O=C=O, carbon shares four bonding pairs (8 electrons) and each oxygen shares two bonding pairs plus two lone pairs (also 8 electrons). The alternative O–C–O single-bond arrangement gives carbon only 4 electrons and formal charges of –1 on each oxygen and +2 on carbon; the double-bonded form is strongly preferred because it places the smallest possible formal charges (all zero) on all atoms.

Step 3 - VSEPR Theory & Geometry

The Lewis structure of CO₂ shows two electron domains around the central carbon, both bonding (the two C=O double bonds). Under VSEPR, two electron domains adopt a linear arrangement to maximize their separation, at 180°.

Because there are no lone pairs on the central carbon, the electron-domain geometry and the molecular geometry are identical: both are linear. The absence of lone-pair repulsion on carbon means the bond angle stays at the ideal 180° rather than being compressed.

Repulsion hierarchy

With only two bonding domains and no lone pairs, the only significant repulsion is bonding-pair–bonding-pair repulsion between the two C=O domains. These are placed 180° apart, the farthest possible separation, giving a perfectly linear molecule.

Hybridization & Formal Charge

In the localized-bond model, the central carbon in CO₂ is described as sp-hybridized: two electron domains correspond to two linear hybrid orbitals that form the σ framework of the two C=O bonds. The remaining two unhybridized p orbitals on carbon form the two π components of the double bonds (one π bond with each oxygen).

Each oxygen is typically described as sp²-hybridized in a localized picture, using two sp² lone pairs and one sp² orbital for the σ bond, with the remaining p orbital contributing the π bond.

Formal-charge check

Formal charge = valence electrons − nonbonding electrons − ½ × bonding electrons. For carbon in O=C=O: 4 − 0 − ½ × 8 = 0. For each oxygen: 6 − 4 − ½ × 4 = 0. Every atom therefore has zero formal charge, confirming the O=C=O representation is the dominant contributing structure.

Modeling Note "sp hybridization" is a useful localized-bond model for structure prediction. Modern quantum-chemical treatments describe CO₂ with molecular orbitals and delocalized π systems rather than literal hybrid orbitals as physical observables. The sp description remains valuable because it correctly predicts the linear geometry and the two perpendicular π bonds.

Is Carbon dioxide Polar or Nonpolar?

Carbon dioxide is nonpolar. Each C=O bond is individually polar because oxygen is more electronegative than carbon, so each bond has a bond dipole pointing toward oxygen. However, the molecule is linear, so the two equal bond dipoles point in exactly opposite directions and cancel by vector addition.

The net molecular dipole moment of an isolated CO₂ molecule is therefore zero (or immeasurably small). This symmetry-driven cancellation is the key reason CO₂, despite containing polar bonds, is classified as a nonpolar molecule.

Expert Quote — Structural Chemistry Perspective

"The decisive point is not that the C=O bonds are polar, but that the linear geometry makes their dipoles antisymmetric. With two identical bond dipoles separated by 180°, vector cancellation is exact; the molecule's symmetry, not the absence of polar bonds, is what makes CO₂ nonpolar."

Interpretation consistent with standard molecular-symmetry and VSEPR treatments of linear triatomic molecules.

This nonpolarity explains many of CO₂’s macroscopic behaviors: it is only weakly soluble in water (reacting slowly to form carbonic acid) and mixes readily with other nonpolar or weakly polar gases. In contrast, the polar bonds are what allow CO₂ to interact with nucleophiles in chemical reactions such as urea or salicylate formation.

Structural Comparison Table

Species	Formula	Central Atom	Electron Domains	Molecular Geometry	Polarity
Carbon dioxide	CO₂	C	2	Linear	Nonpolar
Carbon monoxide	CO	C	2	Linear (diatomic)	Polar
Sulfur dioxide	SO₂	S	3	Bent	Polar
Carbon suboxide	C₃O₂	central C	2	Linear	Nonpolar
Ozone	O₃	central O	3	Bent	Polar

Practice question If one C=O double bond in CO₂ were replaced by a C–O single bond, what would happen to the central carbon's formal charge and octet? Re-derive the preferred structure and explain why O=C=O remains the dominant Lewis representation.

Looking for industrial bulk or specified-grade supplies of Carbon dioxide (CAS 124-38-9)? Browse Supplier on Guidechem →

FAQs

What is the Lewis structure of CO₂?

O=C=O with two lone pairs on each oxygen. This satisfies the octet rule on every atom and gives zero formal charge throughout.

Is CO₂ polar or nonpolar?

CO₂ is nonpolar. The two polar C=O bonds are equal and opposite in the linear geometry, so their dipoles cancel.

What is the bond angle in CO₂?

The O=C=O angle is 180°. Two electron domains around carbon give a linear arrangement with no lone-pair compression.

What is the hybridization of carbon in CO₂?

Carbon is sp-hybridized. Two linear electron domains correspond to two sp hybrids for the σ bonds and two p orbitals for the π bonds.

What is the CAS number of carbon dioxide?

The CAS number is 124-38-9. PubChem (CID 280) and NIST both identify this CAS number with CO₂.

References

PubChem, Carbon Dioxide, CID 280. Molecular formula, CAS number and molecular weight (≈44.009 g/mol).
NIST Chemistry WebBook, SRD 69, Carbon Dioxide. Formula, CAS Registry Number, thermochemical and spectroscopic data.
IUPAC Gold Book, "lone pair" and "hybrid orbital." Standard definitions of nonbonding electron pairs and hybridization in chemical structure.
Atkins, P. & de Paula, J., Physical Chemistry. VSEPR, molecular symmetry and dipole-moment cancellation for linear molecules.
Aresta, M. (Ed.), Carbon Dioxide as Chemical Feedstock. Industrial utilization of CO₂ in urea, polymers and catalysis.

Technical scope: Lewis structures, VSEPR and hybridization are model-based descriptions used for chemical communication and structure prediction; actual electronic structure is better represented by molecular-orbital and quantum-chemical methods. Commercial CO₂ specifications vary by grade (beverage, food, welding, industrial, pharmaceutical), and CAS 124-38-9 identifies the substance rather than a single purity specification.

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Carbon dioxide Lewis Structure